Have you check your local True Value/Ace/ or other local Hardware store. Many of these stores have small parts bins. Some more than others... Home Depot/Lowes are not that big on carrying small parts like your screw.
Mom and Pops hardware are...
Ah yes, I can hear it now, just like when the FCC did away with the Morse code requirement for amateur radio licenses. Never mind that the vast majority of radio operators opt for voice over code, the old timers cried foul and gnashed their teeth...