I have about 8 planes on FM recievers now but just bought the Futaba spread spectrum 6EXA FASST transmiter and reciever for the mustang that I am building. I plan to slowly transition into spread spectrum as the prices come down. The Futaba receivers are going for about $90 but you don't have to buy a crystal. They do have fail safe and eliminate the possibility of having your Tx set to the wrong model. I'm still buy 72Mhz single conversion receivers for my small electrics. Century Helicopters has them for $18.50 for receiver and crystal.