Well, much like apple, many people are willing to pay more for a pleasant experience.

I've used several of the cheap Chinese glasses sites and the product quality all seems uniform but some of them have a better curated selection of designs than others. Warby also lets you do the 5 pair try on at home thing which I'd say is worth paying a bit more over the rock bottom price.

As far as the funding, I'd guess it's because they've been quite successful, and also because they're apparently in talks with Google regarding Glass.