Back in the days before ebay became Greedbay, I sold several pairs of Klein pliers. All for more than $5.00 but certainly nowhere near what these are bringing.
I think Mathias Klein started in business in the late 1850's and apparently made linesman pliers beginning somewhere between 1857-1860. Since nobody was keeping track, it's a little difficult to be definitive on the exact date.
The real question is: When did they begin to forge the date codes on the inside of the handles? Knowing this fact would sure make it easier to spend a large amount of money on a pair of old pliers.
Mike