Zappos is the shoe-version of Amazon. In other words, if there's a shoe you're looking for, you'll find it on Zappos. You may not see the lowest prices on Zappos, but you will find the highest quality and honest reviews.
They are the outlet store of Zappos. In other words, if you find something you love at Zappos but don't want to spend the money on, check again at 6 PM and see if you can snatch them for an even better deal.
If you're looking for the most fantastic selection of discount shoes, look no further than Zulilly. As their tagline says, Zulilly is a ‘new store every day.' That's because they buy the excess stock when stores have the shoes on sale.