Google sells the 16GB Nexus 5 for $349, so on the surface this doesn't seem like an amazing deal. However, Google charges you tax and shipping. It really adds up. You're lucky to get the N5 out the door for less than $400, depending on where you live. Or you can just pay a lot less and buy it on eBay right now.
This is a new unopened Nexus 5 with a 1 year LG warranty that can be used on AT&T, T-Mobile and Sprint.