Where do you find these $1, $5, $10, $20, and $50 sections on skatewarehouse? I know the site pretty well, but I've never come across these sections.
Also don't you guys think 1$ sunglasses are too cheap for optics and it could damage and fuck up your sight?
It's late for me to post that, but here goes: They won't damage or change your eyesight. The main issue with fake sunglasses, lenses-wise, is the lack of protection against UV rays. So you'll be just seeing darker with no real protection at all. Shitty glasses, fake or not, will sooner have problems with the frame than with anything else, like having the paint peel.
That being said, you could always get new lenses for your glasses in the optician if they're sturdy enough, and order them according to your medical needs, if such is the case. I am nearsighted so I make them to my prescription. The prices for sunglasses are artificially high, since most of the famous brands are owned by a single company, which is Luxxotica. So I think you'll be fine if you get those. I'm not familiar with the company, though.