I would be DEVASTATED if my bike were stolen, and I'm not 12 and can buy my own bike!!!! I'd rather have them steal my car!
Have you checked with your homeowner's insurance company? I'm not sure that a kid's bike would make it worth the claim, but you can certainly try.
Heather's idea of writing a letter to the newspaper is a good idea. Also, try
http://www.craigslist.com - there is a huge bike community in the Bay Area and I think you'll get a lot of community support through that website -- I see postings like that often.
Good luck Beep. I'm sorry about the bike and the no-ped. Tough lesson to learn at only 12.
We are ALL going to be a-ok!