I think this is a great idea, but I'm not sure we need to re-invent the
wheel here. There are existing auction sites that will do what needs to
be done. SYI, for example, has been mentioned here in the past (and I am
taking a look at them again getting ready to list some stuff.) And if we
approach such a site as a group of interested people, they are more
likely to incorporate things we would like to see.