Regarding the Market Archive, I probably miss something regarding how it works: I see "sold" titles have a special flag. Fine. But among the unsold titles, I noticed that often the following happens (especially if the ad lasted shortly): if you check the collection of the seller, the advertised and archived machine is listed among the "owned in the past". That means that the machine has actually been sold.
So how does it work in the Pinside market? When you sell a title you are supposed to pay 15$ to the site, right? Is the communication of a successful sale left to the honesty of the seller? If not, I guess lots of sales actually happens, but they are not recorded, nor the value of the sale (for statistics regarding the value of the machine).