I have to agree with the silver mirror in the above chart, but would also say copper is most useful if you're fishing dirtier/muddier water.
As for price point, the total cost doesn't matter as long as they're actually polarized. Most of the time once you're over the $100 point you're paying for the frames and/or the brand. Even though I spent like $200 on the Ray Bans in my avatar, I still managed to have them fall out of my shirt pocket and 3 m deep into a sanitary manhole. Although they did last me like 3 years to that point, longer than any pair of sunglasses to date, and the only time up until then that I've spent more than like $50 on sunglasses. If I spend more money on them I'm going to take better care of them.