Some Important Groundwork
Middle-Age warfare and the cost of armies varied greatly. Some areas expected you to heed the commands of your local noble, paying your own way, meaning that it doesn't cost them anything to put together. Other times, the noble in question decided to hire mercenaries, outfit their conscripts, provide arms and armor, and so forth. This means that the cost varies quite a bit, and it depends on whatever social constructs are present in your world.
It should be noted that most medieval wars were fought with a class of people called "freemen." These were not the peasants which worked nobles' lands. These were individuals who had the right to live in cities and move between regions as they would like to. Freemen would eventually grow to encompass most of society, but that is neither here nor there for this question.
Just like today, individuals of different ranks and abilities also received different pay. Your military structure may change depending on who is available, experience, politics, and so forth. The composition of those 1 000 armed men is really important. For example, in the battle of Agincourt, the English had 7 000 archers and 1 500 men-at-arms, while the french did not retain those proportions at all.
You could buy a live, whole chicken for a half pence. Given that buying an egg-producing hen today costs about 20 USD, that means that 1 pence (in the 14th century) = 40 USD. That's a pretty steep exchange rate, but the income disparities then were huge. If you go with your $5, non-hand-plucked, non-organic, raised-with-modern-agriculture chicken, then the estimates here go down to 1/8 their cost. Obviously, all calculations here are an estimate based off of this exchange rate; take these as back-of-envelope estimates, not the end-all final say on this subject. If you develop a better exchange rate, please use that. It should be noted that values in pence are more accurate.
It should be noted that you need most of your population, as an empire, to produce grain and money so you can go off on a campaign. One of my sources claims that ~7% of your total population can fight without causing famine back home. That helps put numbers into perspective.
The Cost of Soldiers
The sources I found resulted in me determining the following daily wages:
- Footmen: 3-4 pence (120-160 USD or 1 g 20-60 s): men wearing armor, having no horse. Likely the bulk of your army; we can call them "Light Infantry"
- Men-At-Arms or Squire: 12 pence (480 USD or 4 g 80 s): trained soldier, heavy armor, very skilled. Call them "Heavy Infantry."
- Knight: ~24 pence (960 USD or 9 g 60 s): Heavily armored troops, with mounts.
- Archer (unmounted): ~6 pence (240 USD or 2 g 40 s): very useful, but need protection
If you have the composition of the English Army at Agincourt, requiring that your army must buy its own food and gear, and scaled to 1000 men (176 men-at-arms and 824 archers), they require 7056 pence, 89 424 USD, or 894 g 24 s per day. That english army was considerably cheaper than the french one they faced at Agincourt.
If you wanted a more rounded army, with say 750 footmen, 500 archers, 500 men-at-arms and 250 knights, that costs around 18000 pence, 252 000 USD, or 2520 g per day. Knight and men-at-arms are very expensive, but they are trained to fight and that cost may be worth it. This also assumes that these people are not mercenaries or somehow have higher commission than normal.
Assuming magi, generals, and siege operators average out in pay to that of a man-at-arms, we can calculate how much per day your army costs. I feel this is reasonable because magi may be very expensive, but most siege engine operators are not and are likely more common. For your army of 100 knights, 400 footmen, 400 archers, and 100 miscellaneous other skilled individuals, that would come out to 6400 pence, 256 000 USD, or 2 560 g per day.
You ask for:
- 100 horses: 1 for each knight, at least 5 pounds apiece, or 240 pence (24 000 pence, 960000 USD, 9 600 g total)
- 100 sets of knightly armor: 16 pounds, 6 shillings, 8 pence per set, or 3920 pence a set (392 000 pence, 15 680 000 USD, or 156 800 g) Armor was expensive!
- 800 hauberks: assuming these come with a free helmet with every purchase, 5 pounds per hauberk, 960 000 pence. Converted, that's 38 400 000 USD or 384 000 g. This covers the armor of your infantry and archers.
- 600 Spears: the medieval weapon-of-choice. This is really a catch-all for bills, lances, and halberds. Good news is that they're mostly wood, so that reduces cost. Maybe around 100 USD per new halberd. So 60 000 USD, or 600 g.
- 600 Swords: most swords were considered side-arms. Therefore most men need one. Something like a messer or arming swords. Swords were actually pretty common, as Matt Easton (historian and HEMA instructor), says poor quality or old ones cost around 2-3 pence in the late medieval period. 1200 pence, 48 000 USD, or 480 g total.
- 500 bows: even at 250 USD, which you can buy some warbows for, 125 000 USD total, or 12 500 g.
So that's 563 980 g to raise the equipment of an army from nothing. However, most knights and men-at-arms own their weapons and armor, so you can negate most of this cost. You have said that most individuals already have weapons and experience fighting, so I will not include this in the final cost, as I assume they have armor and weapons already.
Since your people are very martial, I am assuming they have their own swords and bows, and the knights have the equipment they need as they are professional soldiers. They fight for a living, so they want their own sets of armor and weapons.
If you are only paying for the hauberks and the halberds/bills, the cost jumps down to 384 600 USD or 3 846 g. These are one-time costs, and will make it into the final total. As long as the metal and leather gets oiled, these weapons and armor will last a long time. Oiling a sword and leather does not take much oil, but I'm unsure how much this will cost them.
Every army needs supplies, and usually close at hand, or close enough to march from the camp to the battle, fight, and be back again within a day or so.
You've specified that you need craftsmen, at least one of each pertinent type. Really, you're looking at several blacksmiths, weavers, tanners, and carpenters. Some of those carpenters are really bowyers, people who make bows, but I'm going to assume that they're paid similarly as carpenters. My sources say that the daily wages look like:
- Carpenters: 2 pence (80 USD or 80 s): makes all your wooden things, like staves, bows, siege engines. Follows directions from master carpenters.
- Master Carpenter: 3 pence (120 USD or 1 g 20 s): directs carpenters, dictates plans for siege engines, and may even do some of the more tricky woodwork himself.
- Master Weaver: 3 pence (120 USD or 1 g 20 s): makes your clothes. This is important for armor, as every piece of armor needs padding underneath to protect the wearer from the metal of the armor, in addition to combat itself. Obviously, your master weaver will have apprentices and journeymen working under him/her.
Those are the daily wages that my sources mention. I could not find another reliable source for the wages of blacksmiths or tanners, but I'm going to assume blacksmiths and carpenters are paid about the same, and tanners also do your leatherwork, which makes them as valuable as your smiths and weavers.
So, a couple of masters of each craft plus 3 apprentices per master should not be that much. At least, not much when compared to the cost of the army. Around 3 pence per day per master, 4 sets of 2 masters (8 total), 3 apprentices per master (24 apprentices), and those getting 2 pence or less each day, gives us around 72 pence, 2880 USD, or 288 g per day.
You gotta feed 1 000 fighting men, plus 32 other people. The national association of wheat growers says that 1 bushel of wheat is enough for 90 whole-wheat loaves of bread weighing 1 pound each. Since agriculture is this kingdom's main economic focus, I will assume food cost are low. So 1 bushel costs .59 pence, ale .75 pence, and so forth. (See the sources below!)
Your fighting men are on a high-calorie diet (like those of athletes) so they can have the strong muscles and energy they need to pound their enemies into dust. I have assumed they have similar activity levels as athletes, days of long marches or battles will very likely increase their caloric needs. Not to mention the marching and training they undoubtably need to do. So that's a 3 000 calorie diet for each of them. Each soldier, if fed on bread alone, needs around 2 loaves per day to be satisfied. That's 6 000 loaves, about 67 bushels, around 39.9 pence, 1 574 USD, or 57 g 4s per day to feed each man just bread.
Steer give your around 65% of their body weight in usable meat, so you can assume to get 750 pounds of meat per cow. You get around 800 calories from 1 pound of raw meat, so that's 560 000 calories from one cow. If you eat ~5.3 cows per day, you can feed your men on beef alone. (5.3 cows * 72 pence per cow = 381.6 pence, 15 264 USD or 152 g 64 s) Really, you're not going to do that. It is very unhealthy.
Let's go with assumption of half of the calories from beef and the other half from bread. That's is more balanced and will result in healthier men. So that's the cost of the beef halved (76 g 32 s) plus the cost of bread halved ( 18 g 7 s) to give you 94 g 39s per day to feed your men.
Obviously, whatever diet these men have will change the price, but I assumed beef and bread as those are staples for traditional European cuisine. An actual army in Europe in that period have other alternative food sources, but you may calculate them as you will.
The Grand Total Per Day
104 g 39s (food) + 2 560 g (pay) + 288 g (camp) + 3 846 g (equipment) = 6788 g 39s for the first day
2 942 g per day thereafter. (Good thing you don't need hauberks every time!)
It should be noted that these do not include many small things, entertainment, or arrows. This is an estimate covering most basic costs; a "ball park" estimate.
Good Sources Used in This Answer
John Savage wrote an article about "keeping your fantasy army a little less fantastic."
There is also an ugly, but informative page from United States Naval Academy on the costs of war in England around 1270-1400. It also lists the costs of common food items and armor in the correct period.