[Business] BYOD for Business Class!!!

I just got off the phone with a rep that had to "check" to see if business class BYOD was "ok in my area" -- and low and behold... it IS!! Questions for the folks that know their stuff. I currently have the SMCD3G (rented for $10 a month from Comcast). I understand that this model can not be bought... is that correct? If so, what is the "next best" that I *can* buy. Anything else that I need to know about making sure they don't play any games when going from the rental to the BYOD scenario? I am concerned that they're going to give me grief... Thanks, Pete :)