To hold down costs manufacturers use cheap materials; usually fibres that are ill-suited to more than a couple of year's in direct UV contact. Martha Stewart doesn't care! nor does K-Mart. If you put up a big enough stink they might replace the entire unit just to be rid of you. Copying a clearly defunct top only guarantees another that will fit poorly, if at all. Whenever a customers says, "It's OK, just copy this one" all liability falls on their shoulders! if it doesn't fit properly it's not our fault... as long as our "duplicate" matches the tattered one given to us! Remember that.

The 3 I recently made were made from 100% solution dyed acrylic fabric ("Sunbrella") and stitched with 100% polyester thread in 92 weight. They required about 3 yds. ($60) and took 1 1/2-2 hrs. to pattern, cut, and complete (between $75-100 labor). Not cheap, by a long shot, but the covers I made will last minimally 5-6 yrs. before requiring a restitch to reinforce degraded thread.

The fabric is tough, I've seen "Sunbrella" last 10-12 years with good care (my awnings are pushing 10 yrs., I've restitched them twice and they're out from April-November in all conditions). Thread is the "weak link", and the first thing to fail under relentless sun. It would take me about 15 minutes to completely restitch a cover ($15-20/every 5-8 years).

Not what you want to read, I'm sure, but I hope it helps!