I lived for years with one pair of eyeglasses at a time. This is the model that I'd argue over 90% of eyeglasses-wearing Americans live by. First of all, eyeglasses are traditionally expensive, and secondly, they're really, really expensive. Who buys two pairs? Rich people, unlike me.
This online eyeglasses thing is a huge deal for us "common people", but there is a catch. Even with fast shipping, it's going to take a week (maybe two). Why wait when you don't need to? You can get a spare pair now starting at less than $8 (from EyeBuyDirect), but even at a multiple of that low, low price, you really ought to prepare for that "uh-oh" moment on which the jerks at LensCrafters have based their profiteering for years.
The high cost of eyeglasses has been a brilliant marketing move for them. Make eyeglasses so expensive that people won't have a backup and when those break, they'll be desperate for their "next fix", and we'll be the only ones here to serve them.
Thank goodness we're free of them.
Take stock in your eyeglasses stock. You can deck yourself out in a couple of pairs, and a sunglasses for each car and still have money left over for that iPhone you've had your eye on -- or maybe fill a cart at the grocery store, and be able to see what you're putting in it?