I'm not sure what a snap-box is, unless you're talking about a ball trap that you can shoot into.
Reballs are quoted by the manufacturer to be able to be shot over 600 times each (but that number factors in the idea that they're hitting hard surfaces and being stepped on and kept in large containers where the bottom balls are squished, etc). So if you're taking care of them, I imagine they would last more than 1K shots each.
If you have old curtains/sheets, you can hang them up (spread open) loosely from a ceiling and drape the bottom into a 5gal bucket and that should catch and collect most of them.
Kansas City, KS