Have you considered making your own? I made my topper for my table to basically inset my machine so the bed is level with the entire surface of the table out of foam insulation and vinyl very very cheaply (like, $20-25?). I followed this youtube tutorial by Marguerita McManus (
https://youtu.be/g14govA4pIM) except the insulation they had at my hardware store was a little different. Most stores will do a couple cuts for free, so if you already know the dimensions you want, it's even easier! I love it, it's fantastic to have such a huge surface to quilt and work on, and it was super cheap
One note: I taped down the sides of the vinyl to cover all the exposed edges of the foam so that there was no concern about the quilt pulling up the edge of the vinyl. She leaves hers loose in her tutorial, but I used packaging tape to tape everything down and 5-6 years later, it's still holding together perfectly.