My inclination on LLL.org values are (no real data crunched, just casual observation) ---- the worst letter combinations sell for around $175 to $200. Really, though, only the absolute worst sell at that price. A combination of two good letters with one okay one tends to start in the $300-$400 area. All premium combinations are around $500-$700. Premium combinations that are repeating, all premium pronounceable, or other very nice acronyms tend to be difficult to find. When they are on sale, they rarely sell for less than $1000.