Do you mean prismatic lenses? I had awful headaches at one point and the optician added prism to my prescription, I don't think the cost changed at all (UK optician).

I believe prismatic lenses are normally used to correct muscle weakness which may cause eye strain (and double vision in severe cases). My prescription was changed back to no prism after a few years.

Edit: siblings are likely correct after reading your comment again. It's likely astigmatism which I also have. But $600 is still ridiculous.