Anyone work with Otto's BMW in West Chester PA? Did some test driving there and it seemed nice enough. I plan to go there during this snow storm and see if I can get a deal on an 2004 M3 convertible with nav. Any last minute negotiating advice from those who have bought before? Do BMW dealers have that disgusting 'Advertising cost' I have heard about? Is that ever real? (saw it at a Nissan dealer)