When I looked at the auction that was linked, it said the camera went for $4100. While Don is a great Leica repair technician, and has done numerous cameras for me over the years, I'm not sure I'd call him a "giant in the industry". He's a good guy who does good work, but we're not talking Oscar B here.
Who knows why people pay what they sometimes pay for things on eBay. I once was convinced by a friend to list some old motorcycle bodywork on eBay, that I had planned on just pitching in the trash, and someone gave me $1400 for it. I was flabbergasted, but as they say, "What the market will bear."