people just aren't paying much for used cars these days--especially highly modded ones or 'swapped' cars. if you wanted to get $8-10k, the car would likely sit until the right person came along. i just sold my '87 fox for $4600 a couple months ago. great exterior, great stock interior, ported GT40 head/cam/intake/full exhaust, tremec 5 speed, suspension work, etc. i had no bites at $6k. as soon as i hit $5k on autotrader, every dirtbag in the world came out to dip their balls in my mashed potatoes. sure, the car was not a turbo car, but i had 15k miles on the drivetrain.
some people avoid swapped cars because they assume things might not be done as well (wiring, setting up the subframe to accept the drivetrain, etc.). or because they'd rather not complicate things like having to mix and match things from two cars when there are turbo foxes on corral.net in the same price range all the time.
either way, the car sounds like a pretty sweet ride---i'd hang onto it.