This seems to be a common practice on Ebay sales. When I was selling some of my really rare baseball cards several months ago I experienced quite a bit of that. You would not believe the amount of emails I recieved on each one of my auctions offering me 10x the current price to end an auction early. Sometimes the offers seem just too good to pass up. I must say however, that if someone offers you $1,000 to stop an auction, you can be assured that the items is worth well in excess of that, so sellers end up shooting themselves in the foot.

Just my opinion.
Doug