You really don't need to build anything custom electronics wise, it's as simple as connecting RX to TX and TX to RX (plus power) with those style of radios.
The RevEd AXE210 can be ordered with an XBee (other xbee shaped devices are available
) a Raspberry Pi and the XBee adapter (the thing I was refering to) is all you need, plug it all in (after you've soldered up the two kits), cut and paste some code and viola, you are in business.
You could also use the Arduino shaped board that Rev Ed do (cant remember the part #), it comes with a proto shield you can use with XBee shaped devices.
@Hippy from advice of the past I was seeking to stick to: inform only