can I get help on finding out what the price of many items would be in a colony in the future or in 3000? I also need to know what kind of ways we could use a colony underwater. Someone please help and let me know early I need this for a project and I need to finish it in a while.
I am in the mood to do your homework. Mine can wait a bit more.
Why underwater? Maybe it is cooler? In a future world where much of the surface is too hot, aquaculture rules. Or maybe the ozone layer is gone and the surface has too much UV radiation to farm in many places. Life has retreated to the ocean.
Prices. You can make it up completely, if it the year 3000 as @AlexP pointed out. Easier would be to put it in the near future: maybe 2050. Then you can extrapolate from today's prices based on the changes you make up for your world, the demand for these items, the supply of these items and the wages your people make in the colony. You can base their wages on wages for a comparable place today. A third world plantation colony would not pay the same wages as a first world plantation.
Check these commodity prices.
Coffee and chocolate and cotton would be very expensive as the areas they can be farmed are now mostly too hot. Animal protein / fiber could be the same or cheaper as seaweed is being used for animal feed. Oil might be cheap because of the availability of fusion power.