Thymio II Education Robot

Hmm..did I mention robotics lately? Your Kid Wants a Thymio II Education Robot - IEEE Spectrum

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.

Of course there are even cheaper systems, like the rubber-band powered Walking paper Robot - YouTube.
Surely every kid should play with robots.
Or then again, maybe not.