How much robot can you get for a hundred bucks? Not much: $100 is about a quarter of a Roomba. A quarter of a cheap Roomba. Or, you can spend it on an open source education robot from Switzerland that will help your kids to learn how to do things besides not vacuuming the floor.
The Thymio II comes from those robot geniuses at EPFL Lausanne in Switzerland. It's an educational robot designed from the ground up to be easy and fun to mess with for people with very limited (or no) previous experience in robotics. It's also designed from the ground up to be cheap, at just about $100 USD. How is this possible, you ask? Apparently, there's pretty much no profit margin or distribution cost, and all you're paying for is the hardware and for some people to put it together for you into a working robot. Not too shabby. And this robot comes with a bunch of sensors and other goodies:
Yes, there's a trailer hook. So you can stop worrying about that. And those "mechanic fixation" points are Lego compatible. To program Thymio II, you can use a nifty graphical interface, or a simple programming language called Aseba that's similar to Matlab. And oh hey did we mention that this thing is open source from source code to hardware? 'Cause it is.
Seriously, $100 seems very cheap for a platform like this. It's cheap enough that a $1,000 grant could outfit an entire classroom with robots that are colorful, versatile, fun, and can be tackled with a GUI before graduating to writing code. There's lots more info along with examples of what Thymio II can do in a wiki that you can check out here, and you can adopt one of your own at the link below.
[ Thymio II ]