It is used by a member to see if anyone wants to buy a piece. I think (my opinion) that some of the interest checks are by people that half heartedly want to sell something but would be just as happy keeping it. Another reason is to offer it here before it is put up on ebay or Audiogon. Some really good deals are found sometime. Once in a while a member also floats an interest check when they have no idea what something is worth. I do not like them as it is not binding in any way and you get your hopes up only to have them dashed at times.