I have seen such items go similarly high. I always wondered if the auction actually closed or if it was a shill bid, trying to artificially inflate the market. Saw this several decades ago with WW 2 Mark 2 knives. They could be purchased for $50 at any pawn or antique store. Then suddenly the action prices were as high a $1,000. Decided it was time to sell some of mine. After selling several I quit selling as the realized price I got was going market prices WELL below what the inflated value was supposed to be.
