How do I put a value on a rare gun? I have checked Gunbroker, Gunsinternational.com, and GunAuction.com for comparison, but none of them have one listed. The pistol is a Smith and Wesson 6591. From what little information I can find, S&W made a small run of them for RSR Distributors in 1990. According to what I found on one of the S&W forums production was somewhere between 350 and 400 units, which S&W officially categorizes as 'rare'. Then were Gen 3 frames, but used some Gen 2 parts to assemble. I have read stories of as new in box being worth approx $1000.00. I have been offered one, verified to have RSR suffix serial number, in excellent condition, but without box or paperwork. How do I determine an approximate value for it?