A free OpenStreetMap based alternative you could use to keep it running in the future:
First of all, congratulations! That's really exciting!
This is a costly mistake to learn, but to offer a bit of hope, at my last start-up we accidentally racked up high costs on the location API. Our CEO hopped on the phone with them a few times and was able to get the bill down. Good luck!
First, find a cheaper API that accomplishes the same goal. Second, email Google billing and see if they're willing to give a discount considering the accidental and non-commercial nature of the charge.
Call Google and I'm sure they'll sort it out
Oh wait, that's not the way Google does support. What you should do is get someone with lots of twitter followers to tweet @google until someone notices this and solves it for you.
Not everyone has enough followers to activate this channel, but surely you know someone who works at Google or has 100k followers?
If this is a first time, Google will make one time refunds if you reach out to billing
hmm me thinks ya business model should have absorbed this and turned it into revenue?
Nope, you should have anticipated & used better alternatives. Just apply the same in the real world & you'll see how your approach changes.
Have you considered asking the moderators of /r/InternetIsBeautiful if you could make a post explaining what happened and asking for some crowd funding?