Nov 16 is the reptile expo in Overland park, Rodent pro will be there and you can stock up. They have this show several times a year. Here is the link
http://coldbloodedexpos.com/kc-reptile-show/
But if you keep an eye on craigslist for kansas city they usually will have a breeder advertising rats and mice on there.Also dont be afraid to ask those mom and pop petstores, alot of them have freezers and sell frozen,thawed.