$3.50 2.4gHz Wireless??

Seen at eBay...

NRF24L01 2.4GHz Wireless Transceiver Module C35

http://cgi.ebay.com/250843587017

From a source in China, 1700 transactions.

$3.50, shipping free. Of course, you need 2 of them. And is 2.4gHz legal where you live?

But! Looks fun!

More specs at the eBay page. Hope someone has time to explore this. Seems you would interface with it via SPI interface.

Here is the NRF24L01+ version and also sold by the pair:

http://cgi.ebay.com/2pcs-Arduino-NRF24L01-Wireless-Transceiver-Module-ARM-/270798071132?pt=LH_DefaultDomain_0&hash=item3f0cd2a55c

There is a large running posting on this device and library resources avalible:

http://arduino.cc/forum/index.php/topic,62222.0.html

Lefty