The 100 dollar an inch is a basic rule that IMO works for most blades UNDER 6 inches. But of co**** material, rarity, flaking, thinness, etc can play a role as well. I'd say anything over six inches of good quality doubles, tripples, or quadruples per inch afterwards. When all else fails, if someone wants it bad enough they will offer crazy money... Supply and demand.
Just my thoughts, nice blade mark.