You don’t say what you’re going to do with your cylinder but could you use something like this, a plastic chair mat, from an office supply store? The plastic is pretty strong, but still flexible. The one pictured is big enough to give you your 4’ diameter, and it’s quite a bit less than $13,000. If you get the kind for hard wood floors I don’t think the plastic has those little cleats in it like the ones for carpeting. And if you look around you might find one cheaper.