If you're still on the hunt for a Nexus 4 and can't get your hands on one, Google have your back with their Nexus Store Locator tool. This tool will will allow you to search local retailers for Nexus devices.
All you have to do is type in your address, and it'll find you a retailer that deals in Nexus devices. At the moment, the only Nexus 4 retailer in the US is T-Mobile, so right now if you're looking for a Nexus 4, then this tool is kind of like a T-Mobile store locator. If you're after a Nexus 7 or Nexus 10, then it branches out a little more.
The Nexus 4 should reach other retailers soon, where this tool will become more useful.