A 1/3 off the market value is a good rule of thumb, but it can be a hard car to sell, even at the discount. It is very hard to get a loan on a car with salvage history so you knock out all those buyers, and surprisingly a lot of guys go to their credit union to get the money to buy a Porsche. What you have to remember when you buy a salvage title car is that the deal you got when you bought it is the exact same deal you have to give the next guy when you sell it. The problem I usually see with salvage/re-built/reconstructed cars is that the guy's who get the deal when they buy it over time attribute the super deal to how smart they are, not to the value of the car and when it's time to sell try to shrug off the stigma and importance of the history, usually to little effect. The market always speaks, even if the seller doesn't like what it has to say.
The best time to buy a car with salvage history is when you plan to drive the wheels off of it. Like a work truck or a commuter car, because when you go to sell the car it will be close to worthless anyway based on condition and miles driven, so the salvage paper is not nearly as important.
The 993 I just bought was re-built in the early 2000's, I knew that before I bought it and if I ever go to sell it, I'll remember it.
---Adam
