Anaren makes a series of RF modules based on the TI CC1101 series of chips. It is low cost and at least as user friendly as the RF12 and RF20 modules and I would argue that they are easier to use but that is often in the eye of the user. They are an SPI interface with separate 64Byte TX and RX buffers. They have internal noise handling as well as the ability to packetize for you to some degree. These are very smart devices and b y design relieve much of the burden from the uProcessor. Like the xBee, they are all FCC certified out of the box in their various bands (European for 433 and 868) and are free to use in commercial devices with the appropriate stickers and warnings.
They are also relatively cheap. Mouser has them for about $16 and Arrow as them for $12.25. Digikey is supposed to have them next month. To be able to get a complete package around a known RF chip with good support in 433,915,868 and 2.4 for this price is phenominal.
The modules as they are currently sold are surface mount but a breakout would be quick and simple since the vast majority of the pins are DNC or NC. Anaren offers a development package with the module on a breakoput with some other components but it seems to be a bit steep at $25.
I would love it if you guys carried these because, as with anything else, it’s the freight that gets you when you have to order stuff from multiple sources and I would rather order everything from here!