We poked around for a while in search of these sandals, finding a smattering of sizes depending on color. The black's soldout on barneys.com, though they have the blue available in whole sizes. Likewise, shopbop.com had the black in a 9.5, and the pink only in a 40 or 40.5.
And then, thankfully, we realized Alexander Wang has e-commerce (aha!), and the site's by far the best bet. Sizes are missing here and there in each colorway, but for the most part, they stock the Fabiana better than anywhere else we found.