Serpent took a big hit with the Veteq car. It was too expensive and never ran right. People got tired of the new car of the week Serpent was into. Many switched to Mugen and found it to be a better car. Serpent has gotten much better today with the 950R and the 710.
Check out
www.ashfordhobby.com They strictly sell nitro cars and parts and are reasonably priced. They are helpful with info too.