If you're able to mass-produce this serum (you say you can), presumably cheaply, and if even a low dosage (your stated half a teaspoon) is enough, you have a lot of options. Also, you state that there's a dormant period here: it's a week before any symptoms appear, and the symptoms of Week 2 and Week 3 are vague enough that they won't be seen as a real illness. Vegetarians suddenly starting to eat meat would be a complication, but they won't suspect that they're turning into werewolves; ordinary people would laugh their heads off at that suggestion.
A million dollars is a useful budget, but ill-suited for going the way of an entrepreneur if you're looking at a global scale: you wouldn't be able to spread it very quickly, so you wouldn't get far before people noticed all the disappearances and mutated people, linked them to whatever product (food or drink, probably) you were selling, and acted against you. So that route is out.
If, however, you can hijack an existing global distribution network instead of having to build your own, you're golden. Bribery or subterfuge might allow you to get into some major fast food company's supply chain or factories or so on, and from there you have lots of potential. As an example, imagine if you managed to get your serum into, say, the McDonald's Big Mac sauce. Suddenly, you're in a position to infect anybody who eats at any McDonald's supplied by whichever facility you infiltrated, which is going to be a lot of people. The sheer scope of that also makes discovery unlikely; good luck trying to connect Big Macs to a wild and crazy werewolf-creating disease when so many people eat at McDonald's.
You could also go for directly administering the serum, passing it off as a vaccine or other medical treatment. This is a little iffy, since medical procedures are (I would hope, at least) designed to guard against the risk of contamination, but no system is impossible to break into. John is on a good track in this regard: you'd probably have good success if you offered your serum (with suitable falsified proofs claiming it to be something else, or a way to hide the serum within a legitimate injection) for some humanitarian program to provide medical care in the Third World. Pick a place with minimal monitoring, and you'll get a nice base population of werewolves at little risk. Pick a few more places to avoid placing all your eggs in one basket, and chances are you'll eventually infect a significant chunk of the world's population.
One more approach is dependent on your serum's properties. You have a dormant period of about three weeks before significant (alarming, obviously ill, etc.) symptoms develop, and you mention that it can be spread through bodily fluids including saliva; at that point, it probably spreads through blood and semen as well. If victims are actively contagious for most of that dormant period (if the virus is able to spread from newly infected victims early on, not just when they're running off into the wild), you're in an excellent position; your virus might not induce coughing or sneezing like the flu does, but people still do it occasionally regardless, so you'd get some improved spreading from that.
It's a rather nasty thing to do, but you could try to infect prostitutes, who in the course of their activities will end up turning lots and lots of other individuals into carriers before they run off into the wild, and it would not be easy for anyone to trace it all the way back to you when the first victims no longer have the intelligence or memory to really single out anybody. Bonus points if you can modify your serum's symptoms to include a greatly increased sex drive in the early stages (increasing it in later stages is optional, but the effect would likely persist: the implications and consequences of your werewolves having that massive sex drive post-transformation are left as an exercise for the reader), to encourage further transmission. You'd basically be making a new STI, with the bonus that mere kissing would likely be enough for transmission, and with that long dormant period you are giving your carriers plenty of time to spread it around. Amplify the sex drive of victims, and pretty much anybody who uses the services of prostitutes or has sex with those who do will become infected. You'd most likely see an increase in rape if you did that last part, which (while a very nasty outcome) would likewise spread the infection that much farther.
EDIT: One more entirely plausible route, if you can manage mass production on your budget and available means, would be to get the serum into local water supplies, preferably in multiple widely spread locations to ensure widespread infection. You'd infect pretty much everybody in those towns, and if you select towns high up on rivers you'll likely also get the bonus of significant infection in cities farther downstream. I can imagine gallons of this stuff being pumped into, say, the Mississippi/the Nile/the Amazon/(insert other huge and important rivers of your choice here) and infecting tens of millions of people. Not everybody will necessarily get a sufficient dosage, but enough will that they will in turn spread the virus to most of the others.