That Jeffery 8 bore has been for sale for years, apparently with no takers. It takes a special person to have an interest in one of these. Someone who can reload for an 8 bore and who can stand up to the recoil. In all probability the gun would do nothing more than go to the shooting range half a dozen times and then sit in a safe. Consequently the market for such a rifle is very narrow.

On the other hand, the .50 caliber and lower rifles are easy to shoot, light enough to hunt with, and factory ammo is available for most of them. So there is a much broader market, and it is easier to support the price.

Personally I would be very cautious about spending more than $10K on a bore rifle if it is a double, or more than $5K if it is a single.