Take a look at the booklet in the Download section. On the last page is a part number. If you quote this to your VW parts shop they should be able to supply this booklet and only this booklet. I was quoted £20 for this item recently, although I didn't take it as it doesn't contain details on the DAB aspect of the RNS 510.
If anyone has a copy of the booklet for the RNS 510 + DAB I be greatful for the part number from the last page in order that I might order a copy from VW.