At this point, it's likely that everyone who really wants a Nexus 5 already has one. But if by some chance you don't, an eBay seller is offering it at a small discount that could add up to significant savings. The Daily Deals page is selling the standard 16GB Nexus 5 for $339.99, $10 off of the price you get in the Google Play Store.
Maybe that doesn't seem like much, but add in the fact that you get free shipping and no sales tax if you live outside California, and the savings add up. If I bought one from the Play Store and had it shipped here to Texas, the tax and $10 shipping would make the total $383.22, more than $40 above this eBay price. The phone is being sold in all color variations, black, white, and (blech) red. Worldwide shipping is available everywhere except Algeria, Morocco, Tunisia, and Yemen, though shipping the phone internationally (which isn't free) may make this deal less lucrative. This is the D820 model, with bands specifically for US GSM-LTE networks.
Even at such a small discount, Nexus 5 sales tend to go fast, and there's no telling how many or how few units the eBay seller has. Get an order in soon if you want one.