TrekDesk offers its TrekDesk Treadmill Desk
with free shipping
. That's $30 under list price and the lowest total price we could find. It fits many models of treadmills, folds for storage when not in use, and features a 72" x 34" workspace, adjustable height, manuscript holder, two cupholders, three-level file folder, and weight capacity of 55 lbs.
Note that this item is backordered until August 24, but can be ordered at this price for delivery when available.