VW can get you any radio code if you give them the VIN of the original car where the HU came from and the radio serial number. I got the code of my RNS-510 version A from VW for free because I spent so much money on parts the guys there of the Parts Department talked to the radio tech guy to give me the code.
Anyone that works or has a contact inside can get the code, so maybe those who get the codes have a contact inside, or something. I've seen Radio Code Crackers online as well but not for our generation radios, just for the mk4, I think.