I want to make two Arduino boards communicate over distances of up to 1 Km. Due to the application I will need to us RF transceivers that communicate over the 2.4 Ghz band and support Direct Sequence Spread Spectrum mode. I expect the Arduino to communicate with the RF module over an SPI, but would prefer not to use an XBee device since I would like more control over the protocol. So far I have only found the AWA24S by Artaflex, but it is a bit pricy.
Can anyone suggest an RF module that fits these requirements?