One trick: If you can get the prescription (they're supposed to
  give it to you by law when you ask - and you might have to
  remind them) - is go to zennioptical.com and play around with
  different glasses. I hav...e a high prescription so mine are
  $25-30 but regular prescriptions are $10-$20. You put your
  numbers in - measuring between your pupils is the hardest part -
  order them and wait three weeks and they come in from China. If
  you screw it up - oh well, it wasn't much money. I got to play
  around with purple glasses, pitch black sunglasses (bad idea
  btw) - and all different kinds of frames and tints through the
  years."