I have a similar Mario Kart K'Nex set http://www.amazon.com/Mario-Kart-Wii-Building-Donkey/dp/B0089WQ6L8 that I bought super cheap at Target on clearance a few months ago. Roll around to my son's birthday last month and I can't say I love the thing. Many of the pieces don't lock to each other in a satisfying manner, and some of the contraption-style stuff just doesn't work well. The idea of linking multiple sets is tempting, I admit, but in reality the sets, while interesting, just aren't all that sturdy. I found the instructions in general less helpful than, say, LEGOs as well, and this made some parts of it frustrating.