We raised feeder mice by the hundreds for our collection of green trees for many years. Some were incredibly fancy colors and also made great pets. The same goes for rats, feeder breeders that have been at it awhile generally have very healthy, closed colonies with great dispositions.
I have kept pet rats for well over 40 years now and my most favorites have come from feeder breeders. I've been active in the "pet rat community" for awhile now and one of the most frustrating things for me is how some of the breeders will not acknowledge that feeder rats can be just as healthy and sweet as their pedigreed rats. Heck, the feeder breeders have a LOT more rats in a year or less than most pedigree breeders may raise in their lifetimes. The feeder breeders are not reluctant to cull problems in their breeding programs at the first sign of problems.
For breeders not specifically raising for pets, approach the breeders, ask them if they have a docile line and see if you can purchase a couple when they're still babies and grow them up yourself. I recently picked up 4 blue girls hoping to get 2 sweet ones from a feeder breeder. Well, all 4 have turned out sweet and just as much fun as the pair I got from a pedigree breeder a few months ago...... at QUITE a challenge also!! Just try to get breeder rats AND own snakes at the same time!! Pfffttt!!!!