If its clean (which it looks like it is) its more like a 13k car. Add up the mods he put it into it and I'm sure he's into it for way more than 18k. The thing with mods like the ones listed is he has it tailored to his specific needs and wants. All of us know you're never going to get out of it what you put into it. that being said, given condition, mileage and supporting mods I'd low ball at 16k and see what happens. Also, how long has it been on the market?