I would add in my 1 attempt to keep 1 nerite was not a success. It was very hard to find what it would eat other than diatoms (brown alga) & some soft green algae...& then I went on vacation. It didn't eat any prepared foods, algae wafers, veggies or anything else I tried. I still feel a bit guilty about it & it's been 12+ years. I keep its empty shell as a pretty reminder of my failure. My soft tap water likely didn't help either (sigh) but it didn't live long enough for that to be an issue.
If you are set on trying a nerite, buy just 1 & I hope you have better luck than I did. But dougall is right on the breeding thing, not an easy to do project...I'd pass.