ISP's have been hounding Google to pay for bandwidth at least as far back as when they bought YouTube, and even some countries (e.g. France) are trying to put pressure on them. Their policy has always been to fight difficult and expensive battles to set a favorable precedent. So far, only one company (Orange) has been successful at making Google pay for peering. In 2010 there was a study showing Google's network was the 2nd largest, only out sized by Level 3, and I think I read in a financial report that Google's network is now larger than Level 3's (article here). Google's private network to connect all their data centers operates at near 100% capacity all of the time (via OpenFlow), which was upgraded when it was considered really good to only waste 60-70% of the bandwidth. Google even builds their own network equipment because no one makes anything that will meet their needs. People were acting like Google was new to this networking game when they started to roll out Google Fiber. In reality, Google has a huge network that they manage and on the order of $10 billion in profit every year that will just rot (thanks to the Federal Reserve's inflation policies), unless Google finds ways to reinvest it. It's 3x the profit (and growing) of AT&T and Time Warner Cable combined, which are the two ISP's in my part of Kansas City.
I would guess it costs Google $300 per customer to run fiber, since that's what they charge for installation (waived with 1/yr Gigabit service), but that may not include everything Google pays for. I know they're paying $5 each for utility pole access and charge customers $100 for a replacement fiber jack and $200 for a replacement network box, which I assume includes some overhead in the price. They also do bulk installs by neighborhood instead of going all over to individual houses.
I expect they will roll out service to all 34 of the new cities in 9 metro areas ASAP, as long as the cities cooperative enough. Overland Park, a suburb of KC, had their offer revoked for asking questions. Their council was supposed to be approving the offer at a meeting, but instead decided to wait for clarification of one of the terms of the contract. I guess Google is too busy with people that are begging for service and offering their first born child for them to deal with questions at this point. They have a backlog through 2015 in the Kansas City area (city limits should be complete this year), and they still haven't announced anything for where I live, which is a painful 1/4 mile outside of a service area and less than 4 miles in any direction from Google Fiber. I'm stuck working from home with Time Warner, who also runs the connection at my data center 3 miles away, and requires me to tunnel my ssh session inside another TCP stream to avoid massive packet loss thanks to "upgrades". I never expected to lament losing the speed and reliability of dial up.