Ouch! But at least you know for future reference. My friends and I sometimes call things like these a "stupidity tax." Not saying you're stupid of course, just sometimes we all do dumb things but learn from them
You might want to document that the website says the toll is a different than reality. You might be able to fight that toll evasion fee (I'm not sure how that works in Cali though).
Sounds like you Cali folks have something similar to the EZPass we have in NY. Even if you don't use it all that much it's a worthy investment just so you can speed through the tolls. My mom has one that we used to share because we didn't use the tolls all that much, but whenever we did it came in handy. Now I have my own though because to get to work I have to go over a bridge every day