Definitely take it if they offer $4500-5000. My high line price for those last year was $4275 with the vehicle having gone through the 60 point as well as a detail.
Heck, I would've taken the $4000, just based on the average price. Depending on state, you should have the right to hold out up to 90 days for final settle. Also if you have homeowners, use that for any personal items, non factory equipment, like stereo, tapes, cd's, etc as most will only value those up to $200, and not include the stereo or ipod values. Homeowners will under their "In transit" clause.
BTW, throw me a 1% consulting fee if you like for the help. *Seriously though, nest of luck to you all.