Condition is the most important factor of all. Some of these have been around for nearly a century and have been in rather incapable hands and thoroughly abused. Others have been cherished and used/abused very little.
I found one that was made in '84, the last year they were manufactured. The serial number was only 70 away from the last one ever made.
Yet, even being that new, was SO abused, it cost me $2800.00 to rebuild, and two trips to Nebraska.
I will admit, it's like a brand new one now, and should last me the remainder of my knife making career.
It would be advisable to take someone with you who at least had a clue what one in decent condition should look like.