Yes. it is not easy to find similar sunglasses that lil wayne wearing. I search hard online and finally, some of his sunglasses style. You can have a look at http://www.ebay.com/sch/Mens-Accessories-/4250/i.html?_nkw=lil+wayne+sunglasses, http://www.ioffer.com/si/lil+wayne+sunglasses and http://www.celebrity-sunglasses-finder.com/Lil-Wayne-Sunglasses.html. Hope there is one pair that you want. Good luck.
You can search on the internet by clicking the keywords. Then there must be some pictures and texts coming out. You then base on these similar ones and search on the online store. The price there is suitable. At the same time, you don't need to go to the franchise store to have a look. You could try to buy one online.