I bought some oil from Dorschel when I visited my girlfriend's parents in Rochester. I was surprised they had the correct oil for my car (505.01), since TDIs aren't common in NY.
Vincent VW wanted $28 per quart! I asked the person on the phone several times to repeat that amount, and sure enough, they repeated it. Dorschel was more reasonable, I think $7 per quart. The person at the parts department at Dorschel seemed nice and polite when I visited.
I have no experience with either's service department though. Are you looking for a dealer to purchase from or to have your car serviced at? Why not learn how to do your own maintenance?