I got my DS's last pair from clearly contacts for $8.84 and that was just the postage they actual glasses were free.

If you have your script I seriously recommend checking them out for a spare pair.
They have heaps of frames to choose from (labels as well) and the lenses are included with 100% money back guarantee if you arent happy with them.

He has no problems with them at all and we get his contacts perscription filled by them too for a fraction of the price of the optometrist.