Why not use the transmitter he already has, and just get a "flight pack" for the plane he chooses? GWS markets many different micro electric flight packs that, while designed for a specific GWS plane, can be used in other planes as well.

GWS flight packs include a micro receiver, two or three micro servos, an electronic speed control for the motor, and a battery. Add a receiver crystal, and it's everything you need to fly a GWS plane.