2006 lexus is250 IS 250 with salvage title, what it's worth?

A salvage title will guarantee that you can't trade the car if you decide to get something else. That's why he's selling it in a private sale. Also insurance may be almost impossible to obtain. Most companies that will cover them won't go for collision coverage. If you take his word for what the damage was you're asking for trouble. At least insist on having a good mechanic/body shop, of your choice inspect it. Most experts figure a salvage title drives the price down to half what the book price on a clean title on one comparably equipped would be. Personally I wouldn't touch a salvage title car with a 20 foot pole.