That thing looks seriously messed up. What all are you looking for? Is the engine and tranny Ok? You can get all the wiring etc after market if you decide to go that way. I'd think 3K should buy it and the guy would feel pretty good. Hope the guy was OK who rolled it?
There really isn't much left but the drivetrain even that might be a risk. Weird that the guy would even retain it to sell after his dad lost his life. I'd let it lie in the bone yard myself
If the motor and trans are good, they alone are worth 5k or more. I personally wouldn't sell it for any less than that, but you never know. And since he lost his dad in it he might just want it gone. I'd offer 2k and go from there