Since Google helped make the phone I'm sure they put their own manpower and money into it hence lowering the cost of Research and Dev to nearly nothing.
I'd imagine since Google is scratching their back with early access to software and that they helped make the phone that Google is getting the price at cost or very near cost.
I have a hard time believing that Google is buying these things at $400 and selling them at $350.
Then again retailers need to make money and Google isn't exactly about doing it in the hardware side of the business. These retailers could be buying them at $199 and reselling for more, we just don't know. But either way, this is a good deal for those who are not wanting to wait for more stock. I've bought from Dailysteals and they are obv no Amazon but it didn't take forever to get to me either. Week or so when I bought my S2.
There's one possible subsidy right there. Those hardware and software engineers don't work for free.