unclaimedart.com
The phrase carries an inherent hook. It suggests a story, which is more than most category names manage.
Unclaimed art is a real and surprisingly deep subject with a serious side and a commercial one. The serious side is restitution and provenance research, an active field with institutional funding and genuine moral weight. The commercial side is the trade in abandoned and unclaimed lots, moving through auctions and storage liquidations continuously.
Storage unit contents, estate remainders, abandoned consignments, works held by institutions with no traceable owner, and pieces whose provenance broke somewhere along the way.
The name suits a provenance research resource, a restitution project, an auction platform, a database of orphaned works, or a publication.
Two words, twelve characters, no hyphen, .com.
The name is listed. Offers welcome.