The marketplace is a little different from the rest of GAF - in that it'll always be sorted by the date the listings are created. So "bumping" a post isn't really a thing, as replying to your listing thread won't bring it to the top (like what happens in other areas of GAF). Meanwhile, users can find your items via search or filters. Also, you can change your listing titles yourself and also mark items sold - so there is a bit of customization involved when all the parts are moving correctly.
Listings are good for 30 days so if your item doesn't sell before then it's okay if you re-list it (which will bring it back to the top of the page). For now we're just kind of making sure that as many listings as possible have good visibility, but we'll be constantly evaluating the market as we move forward to make sure it's as efficient as possible for buyers and sellers alike.
I understand. Cheers, mate!