Despite repeated requests and a prominent notice in the "About this board" section, people were modifying their original posts rather than adding a reply. See the following for why that is a Bad Thing (TM Martha Stewart):
http://mugoo.eton.ca/smf/index.php?topic=375.0
Changing the content of exisiting posts causes all kinds of problems with search engines that index the content, but then find it changed - not to mention people who may be following the progress of your topic. For example, when one person sold the items they had for sale, they changed the post to a completely different topic.
This also means that the historical information (keyboard X sold for $Y in December 2006) is lost, and people lose a valuable source of pricing information.
Just add a reply to the end when an item is sold. Start a new thread for a new sale.
Some people were editing the title or original message body when they changed the price on a "for sale" item, but that left the item the item buried in the middle of all the other threads.
If you add a reply to the thread (for example: price dropped to $xx!!), it moves the thread to the top of the list and sets the "unread" flag (an edited title does not).
NOTE: If you need any post removed for some reason, please contact AdminMan, and tell him why.