[Cincinnatus]

I would have the dealer agree to have the car brought to a BMW center or reputable indy specialist for a thorough PPI or agree to allow you to fly out and do it yourself. It'll cost you $300-ish (plus airfare, if you go that route) but it's money well spent to avoid a $47G mistake.

As to what the "market" value is, that'll be determined by what someone is willing to pay. I find both MMR and other reports of "market value" don't factor well for equipment or desirability and they vary widely. See what others are asking for comparable year, mileage and options using the M Decoder to confirm the equipment so you can compare apples to apples. If you find his price is reasonable, buy it. If too high, negotiate a reasonable discount to come into line.