Bluetooth 2.1 EDR sniffer
The only Bluetooth sniffer for classic Bluetooth (i.e. not Bluetooth 4.0/Smart) that is in a hobbyist's price range is the "Ubertooth One": http://ubertooth.sourceforge.net/

For a list of places you can buy it, check out https://greatscottgadgets.com/ubertoothone/

Of course you have commercial bluetooth sniffers from for example Ellisys and Frontline, the latter being the more venerable of the two:


http://www.ellisys.com/products/bex400/
http://www.fte.com/products/fts4bt.aspx