Shoot for $500 if the seller has some flexibility. Is it parked or matte blue? If it truly is a parkerized 1992 edition 1991A1, I'd consider a little more, only because mine has held up so well and I really like parkerized Colts.
[This message has been edited by SamColtFan (edited 10-31-2001).]
I agree that you should haggle it down a bit. I doubt the one you're looking at is really parkerized, however. Colt switched to matte blue in the late 90's, and the chance of finding an old one NIB is fairly remote.