I'm not the OP but I just got new glasses and they were ~$500. The frames were about $180 (one of the cheaper sets in the store and about $60 more than I paid 2 years ago; yay inflation). So the lens were around $300 and took 2 weeks to produce.

I have a severe case of Strabismus (Exotropia) and my left lens requires a prism in order to keep my eyes focused on the same target. The required prism has gotten strong over the years and as it has, the price of the prism has gone up as well. The prism alone added nearly $200 to my lens cost this time around.

All that said, I imagine the lack of competition (the thread topic) is at least partly to blame for this. I highly doubt my glasses cost anywhere near that much, even if they are special.

Frames you can find for cheap if you look around a bit. The lenses cost a lot as I need massive amounts of prism (took me a bit of looking around to find an optometrist/eye doctor with equipment that could even measure it as it is outside of the range of normal measuring machines) on both to ensure that my eyes focus on the same point

The amount of prism is now to the point that adding more is not really possible and thus if it gets worse next step is surgery on the muscles controlling the eyes or intentionally letting one eye look away. Over time the brain starts to ignore the other eye for focused vision (it would still get used for peripheral vision)

But yeah without the prism the lenses are like 30€. Once you add prisms the lenses are around 350€.