If anyone is interested I currently have a working prototype of a TX/RX combo using arduino pro-minis and nRF24L01 2.4Ghx rf modules.

If you shop on ebay its about £2 for the arduino, £1 for the nRF24L01, £1 for the 3.3v module , £15 for the joystick and £3 for the display. For the RX its the arduino, RF24 and 3.3v and then whatever sensors you want and motor h-bridge. This isnt a combat solution, but something for testing with. I also have it working as a full mesh so that you can have up to 30+ rx units with a master and all the rx modules working together and also sharing traffic to other mesh RX units if they are not in range of the master unit.

Its just a basic two channel analogue TX with two switched channels but also has live telemetry back from the RX unit to display Volts, temperature, Sonar distance and a couple of binary channels.

Status display on the TX is with an OLED display and I'm just finishing up the TX box in 3D when the RF24 modules with external antenna arrive.

If there is interest I'll post it up on github and thingiverse if anyone else wants to dabble with it.
tx.jpgrx-mesh.jpg

I'm using it to control minibots (10+) and a wok armoured sonar buoy