NJC’s MSP430 Launchpad Blog has posted this tutorial on how to add Bluetooth to an MSP430 project. He chose the RN-42 module and designed his own breakout board (shown above). He writes:
The RN-42 module, which is available at SparkFun electronics and Mouser, is a very cheap and simple way to use Bluetooth in your project. The best part about the RN-42 module is that it has an integrated antennae and contains everything needed for the Bluetooth protocol. You would be surprised how many modules require a special external microcomputer that contains a Bluetooth stack to operate.
These are even cheaper for what it is worth:
http://www.mdfly.com/index.php?main_page=product_info&cPath=8_47&products_id=63
And they can be had for even less on eBay. RN ones do have a better AT command set though, and easier to read English documentation.