Aren't they just lab mice? You want them cause they have big litters right?

I've had good luck with albino mice from petsmart and petco, as long as you wait till they're 11-12weeks old (usually about a 4week wait after you get them) they have huge litters. I keep the females in pairs and they birth at the same time. My last pair had 23 pups between them. They usually average 20.

But I know nothing about swiss webster mice, sorry.