I'm going to chime in here because I live in the Seattle area and just bought a 2011 X5 out of CA in December (Local dealers never have what I want, and wanted me to wait 3 months to get it)

You will likely pay CA sales tax. I did. It's the easiest thing for the dealer to do. When you go to license it in WA, you take your sales invoice in, they record the sales tax you paid, and if it is different than where you live in WA, they will either charge you the remainder, or credit you the difference. In my case, they credited me a few hundred. (when I bought a Z4 back in 2004 out of AZ, it was exactly the same scenario)

The only sticky bit with buying out of CA, is that the CA DMV can be really slow in processing the title. In my case, they weren't. When the car was dropped off in WA, I got a 60 day temporary plate. Once BMW financial got a copy of the title, I called and they e-mailed me a copy and I'll be going in this weekend to get permanent plates. If the CA DMV took too long, my 60 temp would expire and I might have to park the car but that didn't happen. It only took the CA DMV a couple of weeks for processing.

Hope that helps. let me know if you have more questions about buying out of state. And stay the hell away from Crevier. They suck.

As for pricing, the cheapest I could find anywhere in the western region was $1500 over invoice in SoCal, and you'll spend quite a bit to ship it. I would have jumped on $1700 locally if they had what I wanted.