For 10 and 20 gal tanks, one could very easily build stands, since the weight of the tanks is not too high. I thought of doing this, but my LFS had the little iron stand right in front of me. I calculated the time and effort of building, and just bought one. Many of them can be dissasembled, so you could probably get the small ones online.
You would have to decide what you wanted to breed. It is very easy to breed and raise livebearers. But don't expect to get much of a store credit for them. You will have to raise them for months to a decent size, and will get less than a buck for them. Angelfish always sell pretty fast at the lfs, so they will always take those from you. But for angelfish, you need a bit larger tank (20 gal), or so I have heard. Also, for angelfish, you will need a larger tank to put several in, then let them pair off as they mature. Then you can put the pair in the breeding tank. Most angels these days do not raise thier own fry, so then the parents have to be removed from the tank after spawn, and thereby need thier own space yet again.
So, I find it a little awkward that you want to breed FW fish before you have kept them for a while. Take a look at the breeding section on AA. Aside from livebearers (platies, mollies, swordtails) you might find it to be more involved than just setting up the tanks. BTW- the link above was just my way of doing things. There may be other ways too. I have since bought aquaclear mini filters with the sponge for the intake, I will try that next time instead of the corner filters. One of the tanks has become a mini planted tank now - so I only have one tank to serve for quarantine and breeding.