The Keystone A-9 Criterion is a vintage amateur cine camera from the Keystone Manufacturing Company, a US maker active in the small-gauge home-movie market through the mid-20th century. It belongs to the consumer film-camera category rather than the professional cine sector.

Sales data for the A-9 Criterion is extremely thin: the only recorded UK auction hammer result on file is £100 from 2011, which is a wholesale saleroom figure rather than a retail price. With just a single data point, today's market value is difficult to pin down, and what a Keystone A-9 Criterion sells for in 2026 will depend heavily on condition, completeness and whether the mechanism still runs.