Just buy a cheap plant or a fish and ask the kid that bags it to throw in some pest snails while slipping him a couple of bucks. They'll be too happy to oblige this time and the next.
If not look in the plant tank and if you see any pond snails in there buy out the anacharis, you'll have snails in no time.
If not look in the plant tank and if you see any pond snails in there buy out the anacharis, you'll have snails in no time.