Nerite Snails are listed on many websites as good snails for tanks as they can't reproduce alone. (It takes two). And will only mess up your walls with eggs in brackish water. I want one spine or horn nerite snail, but none of my lfs carry them right now, and websites that actually have them are selling them in minimum of 30$ purchases or in packs of twelve.

If somebody could tell me 1, what websites might sell one for cheap right now, or 2, what time of year they become available in stores like petco where it is a seasonal invertebrate.