Can't wait to get my grandson this model of the solar system for his birthday, but unfortunately it will be quite a few years before he's big enough not to swallow the smaller parts, and savvy enough to have the mechanical insight to build it successfully. The guy in this 
shows most of the build, and like me he is quite in awe of the quality of the kit. I myself built a little robot with a music box inside it recently, and that too came with proper instructions, and perfectly cut to size wooden parts.
Basically, this is easier to do than the proverbial IKEA furniture, and it is much more fun! And at around 85 dollars, it's quite affordable.