This week's featured store is Wawak Sewing. They have all manner of sewing supplies, accessories, and notions including things I didn't even know exist but what really keeps me coming back is zippers! Just one example: they have brass jeans zippers as short as 3 inches, (and up to 11 inches) in 18 different colors! And the prices! (Yes, I know. I'm using too many !!!) All of their jeans zippers are less than one US dollar each. And small orders are no problem. I try to wait until I need several items at once because I hate when shipping costs more than the item I'm ordering but if you only need one zipper you can order just one zipper.
Their selection of buttons seems fairly limited - just standard shirt buttons, coat buttons, etc - but you can buy them by the dozen or by the gross. (some styles) And, as I said, a lot of other sewing supplies and notions, including a lot of stuff intended for commercial/professional sewing like huge, 6000 yard spools of thread. In addition to the things you would expect, like thread, buttons, zippers, elastic, tape measures, bobbins, scissors, sewing machines and parts, they also have things like steam irons, hangers, garment bags, lint brushes... I hardly know where to stop. Just go browse.