The latest newsletter for the Bay to Breakers 12k mentions that they will have a pre-sale email link to those who receive their newsletters.
So, if you want a pre-sale email link, I'd sign up for their newsletters now.
To sign up for their newsletters, click here.
I have done the 98th and 99th running of the Bay to Breakers and will definitely do the 100th running.
Just to let you know that this footrace is more of an event and is often congested if you are not an elite runner.