Apple snails are illegal to keep. The ones u got are called mystery snail.
Some people probably still use the old name they were sold as, and AFAIK a mystery snail is a type of 'apple snail.'
That aside, where are you located Rob? That will help us know who to send you to. I see an ad on Craigslist pop up sometimes from someone breeding them but I can't find the link right now and it might not be near you. Also one of the LFS near me usually has them for a couple dollars. I'm not sure what price range you're hoping for.