Craigslist, sales, flea markets and thrift stores! My 10G cost $20 and it came with a hood and filter at PetSmart. My sister in NC can't get that deal becuse the sale was supposed end at the beginning of the year there, although the sale in SC ends 1/30/10. Not even all stores in my city have the same sale. So call around! I have seen a 29G tank with everything but gravel and decor (this means nets, heater, filter, etc) at a thrift store for $35. GoodWill is a good place to look, though I have seen some rip offs in thrift stores before. A friend of mine down the road offered me a fully set up and cycled 10G for 55, which is about where I am with my current 10 less a heater and cycling. I should have talked to her first!
At a flea market, I found a 10G full set up (gravel, decor, filter, etc) with a stand for $25. Just clean, add water and fish. The guy offered to let me see that it worked too, but I didn't have any cash on hand.
PetCo has $1/gal sales, but you still have to get the $40 hood. I think they're 20 at walmart.
Just shop around. Be patient and have fun. It may take a while to find the best deal, but it can be done. I think a 10G will be what you'll wind up with, since they're mass produced and, therefore, cheaper. However, they're small size means people can keep them if they move and they aren't the hassle that 55G tanks are. I see a lot of 55G on craigslist, but I can neither afford nor accomodate it. I once talked to a guy who drives around and picks up tanks off the side of the road and sells them or keeps them.
Try places like Ross or TJ Maxx for decor. My sister and I set up my other sister's tank with a neat silver candle holder shaped like coral and put it in the tank. Much nicer looking and cheaper than fish decor at stores. Just be careful with painted items.
My sister did try a 5G tank from Wal-Mart and doesn't recommend it. She said it'll work, but it's a cheap peice of crap.
Also, if you want to avoid illness, be sure to buy only a very healthy fish. They're hard to find, but they're out there. It'll still get sick, but there will be less complications and you can catch something early rather than just thinking a new illness is more of an old one.
I think you can do what you want on that budget, but it'll take time and thinking outside the box and pet stores. I do think it will only cover the initial set up, though unless you get used equipment.
I've heard of using plastic needle point sheets (it's a cheap plastic grid thingy) from Marshal's or AC Moore as a divider. That would save money too. Just get some suction cups and anchor it to the bottom and sides of the tank. I've never done it, but I'm sure someone here has.
You're lucky you can have up to a 20G tank. I've only heard of dorms allowing 5G. Good luck and happy hunting!
Last edited by Omega3; 01-13-2011 at 10:55 AM.