Does anyone have experience using group buying programs like the Universal Buying Service (UBS) or Costco auto buying serivce to acquire new BMWs? Whaty kind of discounts should I expect? Do the dealers hate it? Would I be better off negotiating as an individual? Are there specific negotiable items I can expect to get a dealer to be flexible about?

I Contacted COSCO and there were no dealers in New York State but there were some in NJ and Va. I went to a place in Va and they offered $1000 off the '04 530. I have since been offered $2000 off locally. I am waiting till NAV is available and am aiming to get $3000 off at that time.