I've had Natives, Oakleys, Solar Bats and numerous cheaper brands. When I got my first pair of Costas I was shocked at the difference. My eyes felt wide open. They're worth every penny, particularly the 580 lenses. I'm considering ordering a 4th pair.

  kb here    what is so great about the 580 lens  and can you get that lens in amber rx   thanks kb

I have a pair of Serengeti polarized glasses that cost 180ish, and a pait of WileyX that cost 230ish. They are both prescrip polarized sunglasses, and the WileyX are safety glasses. For fishing, I prefer the Serengetis. Believe me, I have been wearing glasses since I was 13, you learn how to take care of them whem they go on your face every time you're awake.

KB, here's Costa's spiel on the 580s:

http://www.costadelmar.com/ourJourney/technology.cfm

I can't really speak to what, if anything, sets the 580 lens apart in terms of technology.  However, there is a noticeable difference when you put them on after wearing 400 lenses.  My comment earlier about my eyes feeling wide open is about as close as I can come to describing what it's like to wear them.  It feels great.

The link I posted also addresses your second question.  They don't make an amber lens in 580 (although the copper lens is what I'm looking at for that 4th pair...), they also don't make 580s in RX.

i use hobie glasses. i like that there made in japan so i know there quality. the lenses are great. takes off alot of glare. and they run about 150-200. i also use amber lenses. although ive never tried costas im pretty sure these are up there on the quality.