I actually farmed snails, no lie, sold Mystery Snails on Aquabid.com and eBay. Shipping got to be a pain and I was only making about $9 per order. You have to have cold packs in the summer and hot packs in the winter, so there's that as well.
It was fun, but if you want to raise multiple colors, you have to have multiple tanks and cull them properly, which I didn't have the heart to do.
LOL, just checked aquabid and the same seller is still dominating the Mystery Snail market since I did it 10 years ago. You go Gu2high!
Damn. Now I'm thinking about ranching some more springtails. Throw 'em in a plastic container with water, lump charcoal and a tiny speck of fish food, BAM, a thousand more pop out.