@John978 The ones sold at Costco, with the aluminum frames and the stretched UV proof fabric don't have to be replaced if the fabric gets worn or ripped. The fabric part can be replaced by a competent upholsterer for much less than the cost of a new lounger. The metal frames last a long time unless someone seriously abuses them.
I do that work in my area all the time. I've repaired 100 of those loungers. The fabric is held in place by nylon rods that slide up into the grooves in the sides of the chair. It's a matter of loosening the bolts on the underside of the chair that hold the fabric taut, removing the end caps from the grooves, sliding out the old seat or back, and sliding on the new fabric that's been hemmed up to size.
You can also order these new seat and back pieces online and there are many youtube videos showing how this replacment is done.