Ive worked in the optical market before.
There is a HUGE markup on frames, like 100-500% in some places. Especially big names like Polo, Gucci, etc. So, haggle if you can (if its Pearls or LensCrafters, good luck)
When it comes to the REAL cost of glasses, its all about the lenses.
Depending on how bad your eyes are, it could cost a pretty penny. The worse you are, the thicker your lenses need to be. But no one likes thick coke-bottles, so they make thin lenses (1.60, 1.66, 1.67 and higher) which cost more as you go thinner.
Your prescription means nothing in terms of cost, its the lenses you choose.
Prepare to pay $100+ per lens if you go thinner than 1.66