It's hard to say since they don't come up for sale very often. I know of one, lettered and what looks to be decent shape, that has been on offer for months at $1495 without any bites. There were only 3000 made, and the SCSW (4th) claims double to triple standard values, so that wouldn't be out of the ballpark.

But as with all such "book values", a gun is worth that amount only if someone is actually willing to pay.