You can get your hands on a Kit of Parts chassis(C-Base or kitbot) fairly easily.
(1) Some teams opt not to use the kitbot, so those materials often go unused. You might be able to contact a local area veteran and see if they're willing to lend you the materials. Chances are pretty good you'll find someone willing to not only lend you materials, but also help out with the build/programming.
(2) If you're set on purchasing your own parts, then AndyMark.com usually sells your run of the mill FIRST products. You can find their
various drive bases here.
- Sunny G.