Woohoo! lol. I think I figured it out. I'm gonna say it's a "shining ramshorn snail."
http://www.arkive.org/shining-rams-h...tida/info.html Very pretty!
Edit: Hmmm, actually, the more I read about them, the more it sounds like they're threatened, so it seems weird that they would be for sale in a pet store.

I'll keep searching.
I still think it's type of ramshorn snail, I'm just not sure which type. Maybe more people can help....
Edit #2: It's hard to tell from the picture, but if it is a red ramshorn, then you may not want to buy it. According to this site
http://www.fish-tank-guide.com/ramshornsnail.html, they "are known to carry various parasitic Flukes that can be transmitted to other fish as well as to humans."

Other types of ramshorn snails don't seem to carry the parasite, though.
Good luck with whatever that is! lol