How much is the cost of public transportation fron san ysidro? Already have fair tickets. What is my best option in order to avoid driving?

The best way is to drive to the Del Mar High School (aka: Torrey Pine High) where parking is free and shuttle takes to the fair every 15min. Return to high school depends on your departure. On Sunday I left close to closing and it took 1 hour to catch the bus to high school. Have fun!

Uber or lift

Trolley to coaster to fair

Parking is $15. Not sure about transportation options though. Hope this will help.