I certainly don't want to sell mine, I bought it direct from HexCode.co.za years ago, but you can now buy them direct from UK distributors. That should protect you from the fakes that are doing the rounds on Ebay.
If you intend keeping your BMW and doing your own servicing, they are money well spent. I bought mine when they first introduced them, and it has easily paid for itself in the savings made by home maintenance versus dealer prices.
I don't know if they share the same protocols, however you will not be physically able to interface an OBD2 connector with the round BMW diagnostic socket under the seat. Even if you could, I doubt anyone has written dedicated software to work with the bikes ecu via an OBD2 scan tool.