I recently put some of my goldfish on craigslist to sell. I'm terribly over stocked, getting a 125 this weekend to help. Anyway! Many people applied, but most people either didn't write back when I asked them questions about their current set-up, water change schedule, and knowledge of the nitrification cycle....OR they did write back but had 4 common goldfish, 4 fancies and a handful of bottom feeders in a 55 gallon. I told that girl that she was currently over stocked, and needed to upgrade her tank, separate the fancies from the commons, and increase her water changes (once every 3-4 weeks...and she seemed proud of that!)
Another guy seemed like the sure thing, he had a 15 gallon, he was going to put one goldifish in there alone, as a display tank at his job. No problem! When I asked about his water changes, he said every 3 weeks gravel vac w/50% water change. When I told him that wasn't enough, he said he'll add an auto-top off, and that his tank was self sufficient...in other words, he didn't know a thing about goldfish POOP and only tropicals. Needless to say, that fish is still here with me.
I only sold two goldfish, both to the same girl...who I actually already knew through my local aquarium club. Anyone here interested in some fancy goldfish?
Anyway, I guess the point I'm trying to make here is, if you only sell to people who have room/knowledge to keep these things, there would be no money to be made.