IMHO, when people are price conscious in this hobby, they focus too much on the cost of airframes and forget about everything else. Sure, you can save some money by adapting an airframe you got cheaply or even for free to fly with. But when you cost out the whole project, it's really not much of a cost savings if you figure it up by percentage. So if the startup cost for an Apprentice were around $450 for everything you need including a radio you can grow with, a comparable sheet foam plane will probably cost you $375 to get flying. Some would say that an extra $75 is substantial, and I won't disagree. However, the sheet foam plane won't fly as well, will take a lot more time to get airworthy, and will likely crash more. When it crashes, how much of the stuff you've bought will it wreck in the process? And then how much is your time worth? How important is it to you that your plane fly well and be fun to take out to the park? It doesn't take much compromise before that $75 cost savings doesn't really amount to much, and in many cases what actually happens is you spend $375 on at attempt that ends in failure and frustration then sell off all you have left for a lot less than you paid for it.

The cheapest possible way to do this hobby is to buy good equipment and the right equipment and take good care of it.