Artworks are sold at affordable prices [6] ranging from £5 to £1500. For many of the works, the price goes up as the edition sells out. The edition runs range from 30 to 10,000 editions. Each work comes with a digital certificate that is “signed, numbered and authenticated by the artist” [7][8] Once an edition is sold out, collectors can resell their works in the online marketplace.
Bill is an art aficionado. He is searching for some particular pieces to complete his collection. The Stillman edition he wants is still being sold on a normal marketplace, while the Grossman edition of pieces has sold out, and is only available  by private seller.
As the Stillman edition sells out, will it become more or less expensive?