Buying a Rocket Ship

Our space obsession has gotten serious now....So the other day Jacob was talking about the atmosphere and how many miles it takes to get out of the atmosphere and into space, which he says is around 60 miles. He then compared it to his dad's  running time which is 3 miles in 25 minutes and how it would be a long time to leave the atmosphere. Jason told him that there are quicker ways to leave the atmosphere by using a rocket for example. Jacob then asked if we could get him a rocket, and Jason told him he didn't have a rocket fund or money to get one. So fast forward to this morning, Jason comes home with four quarters from Grandpa. Jacob is super excited and says " Four quarters is a dollar, and I am going to save these up to buy my rocket ship". I don't have the heart to tell him he can't and how near impossible that is going to be. It will have to be a toy rocket for now.....