T-Mobile and Nexus 4: I cry FOUL!

I've been shopping for a new cell phone for a while.  Apparently I could own an iPhone 5 and it would work at fast speeds with T-Mobile.  But the iPhone 5 is indefinitely sold out, and I wont be able to get an unlocked version for the forseeable future.  So I was checking out the new Google Phone (which weirdly does not have a 4G LTE radio, but otherwise rocks).  Google sells the phone unlocked so it will work on any carrier including T-Mobile. 
T-Mobile, also seemingly excited about having something good to sell, also offers the phone direct from their website.  I was doing some comparison shopping, deciding if I should buy from Google directly or let T-Mobile get in the middle.  I was shocked at what I found.  Look at the prices:

Above: from T-Mobile's website.  Unsubsidized they sell the phone for $500; with a two year contract extension it goes down to $200.
Below: from Google's own website.  The most expensive version possible is $350 with no subsidies or discounts. 

 
$150 difference?  What's the deal?  Is there a gold-plated back, or some hardware upgrade of which I'm not aware?  Otherwise, T-Mobile is saying they offer a $300 discount while actually offering an $150 subsidy, for ordering through them and extending the contract.  I think T-Mobile is full of crap on this particular issue.