I've bought two M5s long distance, both from Chicago and I'm in NC. The first one I flew up and drove home (summer) the current one I am having shipped (arrives today or tomorrow!) and is costing me $1100 for an enclosed trailer. It would cost me around $500 for plane tickets, gas, hotels, etc. to drive it home.
From CA it would be a no-brainer - have it shipped. If possible, get a board member to check it out and recommend a shop for the PPI. Talk to the seller on the phone, forget the emails and texting, that's no way to buy a car.
It seems that I see a fair number of cars for sale in the DC area, so one would think that you could find one locally. Not sure what your criteria is other than no two-tone interior (I'm with you there).
Generally speaking, I think I'd stay away from Craigslist. It just seems like a lot of flaky people buy and sell with that site. Use the BMW CCA classifieds, this forum, cars.com and autotrader.com to find your car.
If you do decide to fly out and check out the car, first get a contract from the seller and send them a deposit. The contract should state that if the car is not everything that it was promised to be, you'll get the deposit back. If they sell the car out from under you, the contract should state that they will reimburse you for the plane fare. And refund the deposit, natch!
HTH,
Michael