I had my car detailed a few weeks ago by Phil Yiu at Detailer's Domain (He's in NJ, about 25 minutes from the city). He recommended a guy who works on all his cars (911T & RS6) as well as his customers. I'm not sure what he charges, but these things are usually $75 - 100 per dent.
His name is Bruno, number is 201-725-0712. Tell him Phil Yiu sent you. I understand his work is very good.
By the way - if you are looking for a good hand wash the Chelsea Car Wash on 14th & 10th Ave does a really good job. Don't run it through the machine, but enter the 14th street side and tell the detail guys you want a hand wash.
Hope that helps.