garage sales and flea markets are the best. i have about 5 tanks to many cause i just cant turn down a 5$ 10 gallon w/ all the supplies, or even a one gallon for a 1$. thats how i get EVERYTHING, i just bought a decortation for 2$ i saw a petsmart for 30. it is the way to go.
I saw a 10G at Petco for $100 and I think that's a ridiculous price for a 10G. It was a bow front so you wouldn't be able to split it that well, but it came with everything, even a heater. I think it was from Tetra. I don't know, I'd never pay that much for a 10G.
I wouldn't pay that much for a 20 long with all the fixin's.. thats outrageous. I think its ridiculous when people on craigslist try to unload a 10 gallon for $75...no matter what it comes with because I can guarantee I'm not going to keep all the equipment a used tank comes with.