All the Exchange forums are ordered this way. Previously, any post in an Exchange thread would bring the thread to the top (BTTT). Posters would bump their own threads, or their friends would bump them for them, or any random comment would bring them to the top ahead of other threads. It got out of hand, with moderators spending a lot of time telling people not to bump for no reason. We even got a new rule: only one original poster bump in three days.
The suggestion to order them chronologically got a long discussion and has worked out well. I think it's over 6 months now. This system is fair to everyone posting since no one gets pushed off the first page by multiple comments on popular items. Also, once you've looked at what's for sale, when you go back, you only have to look at the new items, which will always be on top.
The items can be relisted but only after 14 days. Any changes before that get edited in, preferably into the first post, so they are easy to find for anyone looking for new items or a price drop.
