I second Suncloud. They are not inexpensive, but they are polarized, 100% UVA, UVB, and UVC (not even sure what this one is). I wear them for biking, skiing and sailing, where quality makes a noticeable difference, as well as general driving around town. I ordered a bunch from Zappos and kept what fit and suited me.
If you don't care about any of that stuff, go to Target. I have some more fashionable sunglasses from there that are fine, except they don't fit in the glasses compartment in my car.
