Here is how I bought my 2008 e60 M5 from out of state:
searched auto trader for the car I wanted with the right color/options, etc. Found one in Scottsdale, AZ.
Solicited help from m5board for any members in AZ to check the car out. Found a member willing to help.
Checked the Car's history with CarFax, ran the VIN through my local service center to check service history, ALL was good.
Had local AZ member take the car for a test drive and a PPI at a trusted local Indy in his area. I compensated him for his time. All was good.
I dealt with the dealer over the phone and email. I mailed a check overnight to them. They waited for the funds to clear before releasing the car. I coordinated with them to have a trusted covered transport company to pick up the car and transport it from AZ to VA. I paid an initial deposit to the car transport company, then the remainder upon arrival.
All this was done without me EVER SEEING THE CAR first hand.
I took a risk, but it all worked out in the end.
When the car arrived, I went to the DMV and showed them to bill of sale. Paid the registration fees, tax, etc. Got my plates and off I went on my merry way. I didn't have to show the title b/c I financed some of the cost through my bank. All I did was show the bill of sale, registration, state inspection, etc. I even got a letter from my bank stating as such.
That is how i did it.