Buying female breeder mice online????

Petsmart usually only carries male or female mice. It differs between stores. So if you call the next closest store, you might find that they have females. (even though petsmart isn't the best stock you can buy..)

You can also look for petcos, they usually do the same thing. Or try posting a wanted ad on CL.

If you keep an eye on craigslist, you are likely to find someone with mice for sale/rehoming eventually. But really, since you have one female, that's all you need to get started, as long as she turns out to be a good enough mother to raise up a few babies. If not, and you are really desperate, you could even bottle raise some babies, but that's a lot of work.

Don't worry too much about inbreeding. As long as you feed off any that have noticeable problems and only keep back the healthiest ones for breeding, it shouldn't be an issue. You can always introduce new blood by bringing in an occasional new male.

Join a rat group local to your area on FB. I met quite a few people by doing that. Actually picked up some rats from a lady today. If I ever get a mouser and have to breed mice I'll be getting my mice from her too. She had some awesome fawn brindle ones. I seriously was thinking of breeding them just for the color.