I'm in St. Louis, and I have feeder mice available pretty much all the time. Rats, not so much.
I'm maybe 30 minutes from St. Peters, but I travel through pretty much weekly to visit family in O'Fallon.
You can always looks me up and I might be able to help.
Supplies on the other hand, there aren't many places. There is a nice little shop near me, but as I said you'd be looking at a minimum 30 minute drive. Otherwise, you are pretty much stuck with Petco and Petsmart.
Gale