Your question is timely. I just held back a pregnant feeder mouse, she's got her own 10gallon tank now. And I have been reading up on the subject of breeding feeders.

Some excerpts from the link below might answer your question re "should i get white feeder mice... or should i go with petsmarts fancy mice?"

"my mouse colony came from PetSmart's fancy mice... For awhile I was getting feeders from a smaller local pet store that sold white feeder mice and I kept a few back as breeders. It's those white mice that cranked out a whopping 19 babies in one litter! ... a fancy mouse from PetSmart, she is fully mature and only had 9 babies. Now I'm in the process of raising up all white babies and replacing all my fancy mice with these super breeders!!! ... People who breed feeders want the biggest litters they can get from healthy females. So they are more likely to hold back females who give huge litters. Pet breeders focus on the look and color more than the litter size... a pet breeder often doesn't even want large litters... "
https://ball-pythons.net/forums/show...s-from-a-mouse!