Basically, any quality pair of sunglasses will have plenty of UV protection, and all have more or less the same polycarbonate in the lenses for shatter protection. More expensive glasses do tend to have better coatings for better clarity, maybe higher-tech frames, and better provision for sweat absorption or venting.
Here's what I do: I shop around for name brands that are being closed out. Just a few weeks ago, for instance, I got a pair of Smith Diablo sunglasses from Bike Nashbar for $59retail was about $100 (www.nashbar.com). And they're pretty good sunglasses: nice, light frame (I got mine in redgroovy!), three sets of excellent quality lenses, good fit. Check, too, sites like Performance Bicycle (www.performancebike.com) and Campmor (www.campmor.com). If I was going to drop a little more green, I do like Rudy Project's Kerosene glasses, which now go for about $120 (www.rudyprojectusa.com). Great fit, excellent construction, superb lensesand they're pretty close to your price range.
Look for a set with interchangeable lenses. You'll usually get three: a standard darkish brown or gray tint, a sort of copper color for high contrast across a wide range of light, and yellow ones. The yellow is what "brightens" thingsit's the ideal choice for flat light or heavy overcast, or for activities like mountain biking on forested singletrack.