You wouldn't be the first to be amazed at the prices people pay for some of the things they buy on auction sites. In many cases what they buy are still available new at lower prices as you have discovered and in some instances I think they are just trying to cash in on peoples ignorance (I think I saw a link somewhere here to someone who was selling empty 120 spools with a starting price of $9.95 or something like that).
Just be grateful that you are not one of them.