What about putting the sold items in a code window to prevent the search function from hitting them? I know old versions of vb the search function did not parse code windows. Thus they can keep the sold things within the same thread but they won't clutter up a search?
CODE APPEARS LIKE THIS AND THE CODE BUTTON IS # IT IS DONE TO ALLOW THE WRITING OF CODE WITHOUT EXECUTION
Personally I find it more annoying when searching for a specific item I will have to go through ten threads where the item is already sold but the user still has other items for sale.