Definitely agree with the others to check out some of the local streams around here. I've actually found some pretty colorful neos randomly although most are clear or brownish. Snails are pretty prevalent too and the ones I've come across seem to be a type of trumpet snail similar (or the same) as MTS. You can also just go to some of the petstores here and they'll either give you some (pond, ramshorn, MTS though, not nerites) for free or sell you some for very cheap. Additionally Pets Plus sometimes sells CRS I've noticed, and a number of hobbyists sell RCS culls locally too.