idk, for machines (and other things too) that get SOLD, I'd think the thread could be disappeared with the record of machine and price sold at dropped into a data-list, maybe saving a whole lot of space for both text and topics.
sold prices being a list, and a price average for the item in a summary, could be helpful for buyers to kinda know.
resolved tech issue threads can be more valuable, things happen, nice to find help info. off topic topics like "does anyone smoke CIGARS?" popping to the top forever, naaw, THAT one isnt annoying at all (lmao).