If you know the official VW Part numbers, then join partsvoice.com

This site works for dealers (of any brand) where they have chosen to list their parts inventories.

Just pick the manufacturer and search up to three part numbers at a time. It will then identify the dealer (with a contact phone #) you call and see if they have the part.

You can make deals on old inventory items.

This site is a reliable service and they have been around for some time. I suspect that there are others.