I had an eye exam last December and talked to my optometrist about sunglasses. If you're talking prescription sunglasses yes, they can be VERY expensive. You can also be limited by whether or not your prescription will fit into a particular frame. I ended up getting a pair of these http://www.libertysport.com/products...3&codecolo=387
I hadn't had a pair of prescription sunglasses in years and despite the expense I think I'm really going to enjoy them.