There are plenty of options if you do not want to use pavers as a cover. If you are set on using pavers, then you are going to have to put together a beefy support structure, those pavers are heavy. You will also need supports under the structure - you are looking at a 10' span here. Making such a structure out of stainless steel is not going to be cheap, as you found out. You could go with something other than stainless to save some money. Unfortunately welding galvanized is also expensive. With stainless the metal is expensive, and you do need some slightly more expensive equipment. With galvanized, if you don't take the proper precautions, you kind of die when you weld it (at least something as large as you are having built).
It is also going to be a bear to get into it if you have to do any maintenance. Removing all of the pavers and underlying support so a tech can get in there is either going to fall on your shoulders or wallet.
You could likely make something much easier to remove, and much cheaper out of pressure treated lumber and composite deck boards.
You could buy something from a company that makes such a thing. Again, paver covers for such a large area are going to be pricey.
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