Pitsco is the only vendor I know of for the TETRIX kits used for FTC. They also used to carry the LEGO Dacta and Mindstorms kits, but no longer.
They are an educational materials supplier, and don't do a retail business. You'll likely have to have your teacher order the parts.
http://www.pitsco.com/store/default....ID=62&by=9&c=1
Steve