I had similar situation happen on a dramatically under priced pin I managed to snag. The seller said he knew he was selling it under price but wanted it gone and was selling it for a few hundred more then he paid 8 years ago. He didn't quite realize what it was currently worth. When I told him what it could go for in full working order, he shrugged and said it was OK. He got to play it for years and still sell it for more then he paid and he would not change the price now that I had showed up.
He prolly fielded 20 calls while I was there loading it up too, many offering double what I paid.