Don't they have Erector Sets anymore? Those were the bomb when I was a kid.
Me and a neighbor kid were hard core into those, had the motors so we could make little cars and cranes and everything. Bear in mind though, this was before mankind set foot on the moon so I have no idea if you can still get these.
Lemme google it real fast...
Holy cow these are expensive! Of course, I haven't shopped for toys in a while... perhaps this is the going rate.
Look into the "Eittech" metal building kits. These look awesome! You get little cranks that make stuff move. Nothing is more fun for a budding engineer than turning little cranks that makes metal stuff move.