T-Mobile will launch sales of Google's Nexus 5 starting November 14th for $449.99. That's for web orders only, as in-store availability won't come until November 20th — almost a week later. For reference, Sprint began offering the Nexus 5 today both in store and online at the same price. Both carriers are selling the 16GB model, which lists for $349 on Google Play.
Clearly Google's carrier partners aren't willing to sell the Android 4.4 handset quite that low. More than likely that's because their profit margin would be too low, or even nonexistent. It's widely believed that Google sells the Nexus 5 at or below cost, a strategy retailers obviously aren't keen on. Thankfully the $349 Nexus 5 from Google Play works perfectly on T-Mobile's network, assuming you're patient enough to endure current shipping times.
Update: CNET spoke with a T-Mobile representative that stated the carrier is not increasing prices to generate a profit, and that it in fact pays full retail price when purchasing the Nexus 5 from LG. The inference is that Google is selling the phone at a loss, either to generate interest or encourage customers to buy direct rather than going through their carriers. We contacted Google about the pricing discrepancy, but the company declined to comment.