I dont have any fancy Oakleys, but I have cheap-o safety glasses and some mid-range Serfas glasses.
http://www.amazon.com/gp/product/B00...ls_o00_s00_i00

I can definitely tell a difference in the optical quality. The Serfas have a clearer, sharper lens. Its not huge, but its noticable. The cheaper safety glasses seem to scratch easier, but that could be because I'm less careful with them. Unfortunately, the Serfas gave gone up a bit in price. I think I paid $35 for mine.