I built from the VEX platform, when Radio$hack started clearing out their inventory. I'm more than sure you can find similar parts on EBay, or even (if you're of the sacraligious type) find a tagsale or even on EBAY and find someone selling an old Erector set, which the VEX framework was a direct steal.
I'm still trying to get a tank frame I put together long ago, when VEX still supported the version 1 programming kit. I've since stripped it of the VEX controller, and I'm now trying to build it on the Duemilinova. (if it requires more I/O, I have a MEGA-2560 waiting.) Main problem, is finding time to do the project.. Too many other things going on in normal life, and too many headaches when I go to try something new in the programming, and it doesn't work.