I'd definatly want to go with something that's at least a gallon for putting individual fry in. 1/2 gallon is just too smal in my honest opinion. The fry themselves might be small, but they need lots of space to grow. If you put them into a little 32 ounce cup, it'll stunt their growth, meaning it'll take twice or three times as long for them to get sellable size and form. Not to mention 1/2 gallon and under means changing the water on an almost daily basis.
I'd suggest going to local eaters and grocery stores and asking them if they have any 1 gallon leftover pickle, olive or whatever jars, and if they'd be wiling to give them to you either for free, or for a small price. That way the're cheap, and all you'd have to do is give them a good washing and disinfecting. If you don't feel right going t do something like that, try to find 1 gallon mason jars, or if you're really going for cheap equipment, buy bulk tupperware conatiners at you local dollar store, or see if you can find some at like a wal-mart. Those work perfectly fine and are a great replacement.