So, what should you look for in a pair of sunglasses before you go out and buy them? Trying it on in person is the best way to ensure that it fits properly. If you already know what brand and design you want, ordering prescription sunglasses online makes sense. The fit is hit-or-miss because the virtual try-on tools don't take into account the shape and contour of your nose and face. Heavyglare is one of the most cost-effective prescription sunglasses brands in the United States.