I avoid salvage titles like the plague. There is an old adage that I live by that goes "sometimes the best deal is the one you don't make..."
Salvage means exactly that...that in the professional opinion of the insurance company there was damage in excess of what the car was worth to fix...usually that involves extensive damage to the frame which isn't corrected properly because someone wants to buy the car really cheaply, do the minimum to fix it and sell it to maximize their profit. Rarely do they take it to a frame shop and spend all the $$$ to get the car back to spec. One tip to watch out for is when someone tells you that they've driven it X miles with no problem. All that means is that they haven't encountered a drastic situation where if the structural integrity of the car was severely tested, the car might not perform as well as it should and are you willing to bet your life and limb on that?
Finally, if you still really want the car, spend the $$$, take it to the best independent frame shop and have a full inspection; plus take it to BWM and have a full pre-purchase inspection. The $$$ you spend up front, might save you lots of $$$ and perhaps much more in the long run IMHO.