Hi, I’m Ryan, and I am a sunglasses addict.
30% off on a pair of Costas ain’t bad. You might be able to find cheaper, but I would say you would be limited on selection.
580G with green mirror are sweet. I have a pair. They’re great. I also have a pair of 400G in green mirror and 400G in amber. They’re really nice, too. The biggest difference I notice between the 580G and 400G is that the 580Gs are noticeably lighter.
Frame comes down to face size/shape and personal preference. If you’re unsure, I would go to a retailer and try on some frames to find what you like. Then, order from whatever source gets you the discount.
Some people don’t see the value in good glasses, but my oldest pair of Costas is 10+ years old, and they still look new, so that’s justification enough for me!