Serious question: what kind of servo can you get for < $5? I recently built a robot, and spent $16/motor.

edit: never mind, the original site has a parts list. $2.69 each, he links here, but the site is down right now: http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idP...

I threw together something like this using scraps I had around.

Instead of using cardboard though, I used a piece of acrylic for the base. Then I got a couple of those blank expansion slot covers from the backs of PC cases, and bent them to make another stand-off platform on which I mounted a piece of ABS. On that I put a webcam and Pico-ITX SBC with a SDD affixed to the bottom of the ABS. An NiMH battery pack was put on the lower base between the two servos to keep the CG low.

The wheels were initially blank CDR's but they didn't get very good traction so I eventually found some wheels for an RC airplane. I used a small caster wheel in back.

The moral of this story is always have scrap plastic around. I have built so many small helpful things out of it like a stand for a 7" tablet on exercise bike, etc.

A friend of mine makes a nice light-following robot:

http://www.hackerspaceshop.com/solarroboflower-kit-eco.html

Its not $10, but still pretty affordable, and a very fun project to do with kids ..