Try food service equipment. In particular french fry screen or donut screen. After deep frying, food are usually placed on these screens to allow excess oil to drip off. Food grade stainless steel, mesh size is just right for small food items, come in several standard sizes, prices range from $10-50, won't rust, bug proof, will take high temperatures, can be used with harsh cleaners, and durable enough to withstand unskilled labor.
I spent a lot of time looking for stainless steel screen and a good solar dehydrator design last summer. I found both at GeoPathfinder. He sells the screen in 2'x2' squares. They are about half way down the page.
His solar dehydrator design is on the Food Preservation page. I built a 4'x4' dehydrator based on his design. Rather than have it built into the ground mine is mobile. I have short legs on one end with lawnmower wheels to make it easy to move and longer legs at the other end with multiple holes so I can adjust it up or down tp catch more or less sun as needed. I didn't get mine built until the fall but I was able to dry several batches of pears and apples. It worked great.