Years ago, when my wife was a poor undergraduate student, she decided to splurge a bit and treat herself with a nice pair of Ray Ban sunglasses (about $100). After owning them for only a couple weeks, she accidentally left them on a desk in a computer lab after writing herself bleary-eyed. When she returned, they were gone, and she swore to never spend more than $20 on a pair of sunglasses again.
My thrift scores have been few and far between lately, but when I saw the almost brand-new pair of Ray Ban's sitting in the sunglasses pile at my local store (including their original case and cleaning cloth), I knew I had to buy them. At the time, I wasn't quite sure they were in a style that my wife would like (and I hadn't yet heard the aforementioned story), but they were nice enough to buy regardless.
Needless to say, she was stoked to see what I'd found, as the dark tortoiseshell Ray Ban's were the same exact style of the ones that she'd lost so many years ago.
As I mentioned above, they're immaculate, without a single scratch and had only a single fingerprint smudge on one lens, which buffed off easily with the enclosed cloth. Not too bad for $4.