Google envisioned a $10 unlimited plan in early T-Mobile talks
early designs for Android devices and part of the vision that Google had while negotiating with T-Mobile as its carrier partner. Part of that plan was to push people towards unlimited 3G data plans, because Google knew even back in 2006 that the key to smartphones was in fast and unlimited data. Now, it turns out that Google pushed a plan to T-Mobile which would have seen Google subsidizing customer data plans and offering an unlimited data plan for just $9.99 per month. The subsidy would have been covered mostly by Google not collecting a commission from T-Mobile for referring Android customers.
Of course, Google estimated that users would only use on average about 15MB of data per month for Google services like Gmail and Search (it's unclear if YouTube was part of the equation, but it seems likely not), which is a far cry from the data usage we see now with the rise of mobile video and music streaming. Still, we all know that this plan never came to pass as the G1 was originally released with $25 and $35 data plan options.
source: The Verge