Beat Home Depot, Lowes, and Amazon.
I needed a rare set screw (2 each) for a Singer sewing machine. Home Depot did not have any. Amazon did not sell any. I did an AI search for the set screws and it said that Lowes did not have them also. It recommended FMW Fasteners. I went to the FMW website and found them there. The only issue was a $25 minimum order. I decided to refill my empty screw/bolt bins for the sizes I frequently use, and buy some nice hammer drill bits. FMW did a great job of packing them in separate bags with the screw type printed, and shipped them promptly. Next time I need to order refills, I plan to use them.