Hi,
Can you make a sold/archived listings plugin with reasonable pricing for this along these lines (1,2,3,4) as above and some more features so the seller (or admin) can either select the item as sold or closed and the listing is archived instead of completely deleting (but the admin should have an option to delete the listing or if the user wants the listing completely removed). Admin should also be able to archive any listing.
However, the archived listings should not count towards total listings of the seller so it does not affect if the seller group posting limits per group or posting limits per payment package, etc., and only active/existing listings should count towards posting. May be admin can set how many listings a user can archive, if possible.
Admin should also have control over how many listings can be archived in the database and for how long but be able to delete (override) a few listings at anytime if the database is getting large.
The users can view the item and info, comments, etc, (may be the admin can decide to hide if possible) but the buyers cannot contact the seller on sold listings.
Also, about 3-5 (admin controls) sold/archived listings are shown at the end of search results on each page/category/city/search term etc., (someone previously requested this feature and I like it too).
If you decide to make it then may be I can think of some more ideas but the plugin should work with old and other osclass versions also.