BOE-Bot (Parallax)
Low cost robot (uses Board of Education programming board and BS2-IC) that can be programmed to follow a line, solve a maze, follow light, or communicate with another robot. Available at Radio Shack.

ARobot (Arrick Robotics)
Affordable, completely programmable, expandable, mobile robot platform designed for education

iRobot Create (iRobot Corp)
Affordable programmable robot, pre-assembled to facilitate the development of new robots. Built on iRobot Roomba platform.

Mindstorms NXT (Lego)
Robotic kit that enables the user to create an even more powerful robot than the original Mindstorms - $249.99

Manoi AT01(Kyosho Corporation)
13 inch robot - $1200

SPC-003 and MIRAI RT(Speecys)
Robot kit that has CPU( 133 SH3 or 400MHz PowerPC) , OS(netBSD), specially designed Servos for Robot- Weighs 9-pounds. $6,300