Yes - from the Bay Area and bought an 85D from someone on the east coast, car had 9k miles on it. Wired the money and arranged for a enclosed car carrier ($1800) which provided door to door delivery. Would have been fun to do the Great American Road Trip and fly out and drive it back but I just can't spare that much downtime right now.
I wired the money to the seller and he fedex'ed me the signed title, one of the keys and a nicely done bill of sale that detailed out the mileage, price, etc.
Took about 10 days to get the car. Car was delivered to here on the Peninsula at about 7am and I drove it to work that day.
Had to make an appointment with the DMV to get the mileage checked and transfer the title, pay the sales tax, walked out with license plates. Drove right over to Tesla in Burlingame with the new registration paperwork so they could transfer the warranty. They even put the plates (er, "plate") on for me. Done.
Pretty painless. The only sketchy part is sending a wire transfer for the full payment to someone you haven't met.
There are no shortage of Teslas in the Bay Area but like most cars, I find better deals out of state. People in the Bay Area have a pretty inflated opinion of resale on their cars be it a Tesla or a Honda.
I've bought maybe 6 or so cars out of state, from boring SUVs to new AMG Mercedes and never had an issue, just be sure to ask enough questions so you are satisfied. You can also check the seller on LinkedIn and other sites to make sure they all seem legit. I've passed on deals where the seller doesn't seem like the kind that would own that kind of car. The cell phone kiosk guy shouldn't be selling a $100k car unless there is something totally sketchy about it. Another deal will _always_ come along if you are willing to look anywhere in the lower 48 states.
I bought one in Salt Lake City and drove it back which was fun but to do a cross-country trip, especially one that required charger stops would have to be your big summer vacation. Would be a lot of fun if you have the time.