Decibit 2.4 GHz RF Transceiver Development Kit

Decibit rely on proven technology: Atmel’s ATMega168 microcontroller in combination with an nRF24L01 transceiver chip from Nordic Semiconductor together from the IC complement of a series of intelligent 2.4 GHz (ISM band) transmitter/receiver (TX/RX) modules with ISP connectivity and, remarkably, the ability to run AVR firmware created by you, the user.
Plug & Play but AVRasm too
The DDK kit, advertised at US$ 69 at the time of writing (December 2008) has great educational value as there is so much to discover and develop for different levels of users.