My arduino Wifi controlled Robot

[gixxy]

While not the cheapest, the most user friendly radio system I've used are XBEEs.

As I see it. the best combo would something along the lines of:

An Arduino UNO, Leonardo, or Mega along with the IO Expansion Shield for Arduino V7.1, and the Wireless GamePad V2.0 for Arduino.

Of course you'd also need 2 XBEEs, and a Serial to USB Adapter to configure them.

All in all a ~$168 control system with quite a bit of flexability. Such as getting 2 of these Wifi BEEs and suddenly having not just a wireless connection, but wifi to monitor systems.