They're free, other than shipping, from Estes.
Since the Saturn, Shuttle, and Falcon were not contemporary, it's pretty clear there's a bit of artistic license going on. Not that they would ever have been launched that close together.
I think they left the Shuttle in one piece so you could figure out how to make detachable boosters. My first thoughts about it were to move the dummy fins to mount on the tank, and then mount a third motor in bottom of the tank, in the same plane as the booster motors. It would be better in the shuttle, but that might present some interesting stability problems. The booster motors should be shorter burning than the center motor. The boosters could be mounted by pins in little tubes, supported at launch, and then fall out when they are not thrusting but the center is. Without fins, they might come down sideways and not need chutes. I suppose it would be in poor taste to have the ejection charge blow out the o-rings.
