The Futaba 3PM 2.4g is your best bet if buying new, but if you can't swing $189 right now a great radio that can be found cheap is the Futaba 3PJS. It is a FM radio that can transmit 75mHz FM (or 27mHz but I would avoid 27 mHz FM because receivers are tough to find) or 75 mHz PCM which is much more immune to interference than FM. It's still FM but the signal is digitally encrypted so the receiver will ignore anything other than the TX signal. The 3PJ usually came with a FM receiver and the 3PJS came with the PCM receivers. I handed my 3PJS down to my son and he uses it with the stock PCM receiver, a Hitec FM rec., and a Novak XXtra synthisized receiver with no problems or glitches at all. It was Futaba's top of the line radio before the 3PK and I've seen TX and RX go for as little as $50 on eBay.
http://cgi.ebay.com/Futaba-3PJS-Supe...3A1%7C294%3A50
It has more adjustments than most people would need and you can buy new receivers for as little as $35 with crystal. Definately one of the best used radios for low $$$.