He's not going to save on the radio, but by using the components from the crashed Alpha to put together a Low Winger, he could save the cost of all of the items that add up.

e.g.

Engine
Switch
Servos


If he applies that against a computer controlled DSM radio and an airframe, he'll get what he wants for the amount of money he is talking about... and end up with a better radio to boot... one that could handle multiple planes exactly as you said.

And in a pinch, he could just use the old TX with the new airframe, and then save up for a DX7 later.

That gets him back in the air quickly.