I have a class project that is required to build a stair climbing robot for uner $50. It needs to travel 12 steps in under 60 seconds while carrying an egg safely to the top. There needs to be one switch for turning on and the stairs are about 7.5 inches high with 2 inches of lip on each step that sticks out 1/2 inch on some. We have a variety of additional requirements but those are the main ones. Does any one have any good ideas for parts and design suggestions within the 50 dollar budget?