That sounds about right. I remember having gone to an optometrists office some time back and they were able to cut lenses right there and have glasses ready in an hour. I was amazed and couldn't understand why everyone couldn't do this.
Sunglasses are the worst. They cost basically nothing to make but the profit margin is Inf% b/c of branding. A $20 (at most) pair of non-name sunglasses instantly becomes a $700 pair of glasses once you slap a few PRADA insignias around it.
I used to get my sunglasses from Goodr; they charged $25 for no-slip polarized sunglasses, which were very good. After one of the pairs broke, I decided to get two pairs of Ray-Ban Wayfarers, one for $75, and the other for $200. I knew I was getting fleeced, but I finally wanted a pair of "cool" shades and could finally get them without breaking the bank. :D