This article was in a recent Cabela's Outfitter Journal (I retyped it in part):
Colt Walker Pistol Fetches $920,000
A like new 1847 Colt Walker .44 black-powder revolver, sold with its original powder flask, set a record at a recent James D. Julia firearms auction. The rare, historic Colt Whitneyville-Walker pistol, made for use in the Mexican-American War, sold for $920,000, inclusive of the 15-percent buyer's premium. According to Auction Central News, the sale price represents the most expensive single firearm ever sold in North America and is believed to be the most expensive ever sold in the world. Fewer than 170 of the pistols are believed to exist. This one was in pristine condition.