As a collector, I'd like to easily understand whether a piece is being sold by the artist or someone who has already collected the work. There are a number of reasons, a couple of examples:
Is this money going 100% to the artist?
Has all of this artist's primary work sold?
Activity Newest / Oldest
This is already being badged on the Username > Activity tab under Recent Sales. I'd love to see it in the filter panel and to be able to click on that badge to see