I'm very 'the bigger the better'. I think a 2-gallon is still too small. You can buy a 5-gallon with a lid for less then that, also. I'd try that. I know at Pet Supplied Plus around here, you can get a 5-gallon with a screen lid for 10 bucks.

I'm not sure how the fish scale works. An inch per gallon sounds good, but you have to remember that some fish are aggressive, some fish grow, some fish need to be able to roam, and even a fish can get bored if there is not enough room to explore.

If you ever do end up getting a tank set up, remember to give lots of things to make it interesting... Plants, those little novelty castles maybe... If you don't mind it looking a little unfashionable, toss a few PVC (or PCV? I'm not sure) tubes in there, my neons love those, and bottom feeders really do too.