I have a pair of Ray Ban sunglasses that I have had for at least 6 years that cost over $100.  Stylish, fit well, and very dark.  They get the job done, however, they are not ANSI approved and don't work well at night (of course).  I was at the local dealership a couple weekends ago and purchased a $60 pair of H-D ANSI approved, anti-fog, transition lenses (dark when daylight/clear at night) that work great!  A little expensive I suppose, but, I tend to keep a pair of sunglasses for a long time, so in my opinion...money well spent.