You have to know,when we pay for commodities, not only do we pay for the cost, we also pay for everything the manufactures and retailers cost in the whole procession, such as publicity costs.
For prescription glasses, we pay for the glasses, I mean the whole produce session, and we pay for the prescriptions, it means the doctors need take some profits.
So it may be fair for paying that much, if the quality is really good.
All you need to do is choose a qualified doctor who can give you the best prescription and the best glasses.
The high price of the prescription glasses is due to the good quality of the frames and lenses. There exists the big difference among the quality of different types of glasses. If you want to buy the durable glasses with perfect glasses and frames, you will have to pay a lot of money. You could wear it for many years.
Ok, I can see that you just don't understand why a pair of prescription glasses cost you so much money. So, actually, the reasons might be over here. Perhaps you just walked into a large shopping center, where the cost might be much higher. Or perhaps the brand you chose is of great value. Generally speaking, you could get a pair of nice glasses at a local optical store, or Walmart vision center, where the cost could be quite affordable. Hope you find what you seek over there.