go to Skycraft Surplus at exit 87 off I-4 W from Deland. You will see a Flying Saucer on the roof of their building, do not be afraid, it's made of fiberglass. They might have equivalent or similar screws there, and so many other surplus goodies it takes a whole day to go through every isle in the store. Grommets, Plugs, Wiring connectors, Hardware, you name it. Once you go there, you're hooked.
Good luck finding the screws.