I inevitably break or lose my sunglasses, so I'm done spending much more than $50 on them. I always thought Native was a good bang for your buck brand...they're often on Sierra Trading Post in the $60-$80 range. I'm probably done spending even that much now though as I've gone through a pair a year for the last several years...Cheapos from the rack at Cabelas for me.
The real high end ones do offer better performance IMO...is the difference worth paying for?...that's up to the buyer to decide. If I didn't have such a poor track history with them, I'd considering popping for a $200 pair of Oakleys or Ray Bans.
Polarized lenses will remove some of the glare from the water's surface (better ones will remove more of the glare). Depending on conditions, this doesn't always necessarily make the fish much easier to see. Depends on the stream bottom, water clarity, etc.