We're starting the exact same exercise; something cheap and easy to use that doesn't tie up a roboRIO. We just started brainstorming ideas on Tuesday, and haven't gotten around to evaluating them. We have the complication of having a mechanum on this demo bot.
- RC based: http://www.andymark.com/product-p/am-2827.htm
- generic RC based, and have an onboard RPi/ARduino field the PWM off the receiver, figure out the joystick positions from the pulse widths, and do the mechanum math
- wireless joystick to an onboard RPi/Arduino.
- homebrew remote arduino controller talking XBee (or the almost equivalent Ciseco-made XRF units) talking to an onboard RPi/Arduino.
- remote RPi-based controller talking the FRC protocol over 802.11 to a roboRIO onboard
- remote RPi-based controller (or cellphone or tablet) talking OpenRobot over 802.11 to an onboard Sasquatch we have on the shelf.
- goodness knows what else