You can either get them in the local optical store or shop online. Just shop around at your local place, if you find them , just try them on and select the one that siuts you most. If the price is much high, you can remember the model of the sunglass that you choose, and then go to search them online. The glasses including sunglasses are nuch cheaper online.
Well, it seems that you are quite interested in those Neon Orange sunglasses.
I personally find them very charming. And as a matter of fact, they are so popular that they could be found at a lot of websites or optical centers. You could get a lot of them at some e-commerce websites such as Amazon or eBay, generally speaking, you could buy them for good prices.