<p>I’m not familiar with this event, if you want to give me some more information I can help you out. I’m assuming by robot you mean autonomous and not radio-controlled? (Technically, a radio-controlled vehicle is not a robot, but some people consider it so, i.e., battlebots).</p>
<p>I personally recommend the Boe-Bot kit from Parallax which is fairly cheap as far as robot kits go ($150). However, it is not a plug-and-play system as most “easy to build” kits are. It requires learning PBASIC, learning how to wire circuits, etc. It’s really easy though, since PBASIC is a very simple language, the breadboard doesn’t require soldering, and the book that comes with the kit assumes you have no skills at electronics or programming at all. Excellent forums too.</p>
<p>Some other kits at the top of my head are Vex and Lego Mindstorms. Both of these are twice as expensive as the Boe-Bot.</p>
<p>Hoped this helped.</p>
<p>edit: After doing some quick reading on the Robot Ramble event, it looks like the “robot” is radio-controlled, so I have no experience with that. However, to answer your original question, the sites I purchase my robot parts from are Parallax, and Acroname. The work I do is a little different from what I have read so far about this event though, so that may not be of much help.</p>