What do you do when missing screws?

I live in a small town and the local hardware store only carries a limited supply of things. The nearest home depot also only has a small assortment of supplies.

It was easier for me to buy the interior screw kit from penstar at moparfest last year. I also do not have alot of the screws that were used. The spare car has some of them but seem to be missing the ones i need.