Well it's $60 for kit 01 which has like 5 or so of the "toy cons" in it (piano, fishing rod, house, motor bike, and some other stuff). Kit 02 is the robot thing alone which is $80, and they have a decorating kit that's $10 with stickers and stuff to decorate your creations with. So $150 total for all 3. But yeah I agree it seems a little overpriced for cardboard.
I also thought the same thing about kids tearing it apart in minutes... Which made me wonder if it's more than just cardboard? Maybe it has some kind of coating on it or something to make it more durable than average cardboard? It seems a little short sighted if it's just your everyday flimsy cardboard so I feel like Nintendo would have thought it through in some way.
Also I don't think it'd be something you could print off yourself as it looks like there's more to it than cardboard. Like the robot suit and fishing rods have some kind of string, too... And who knows what else. Considering how it works, I'm guessing there's something you'll need that the joycons can detect to make it actually work as well.
Still totally want to get at least kit 01