Burbank, CA 91505
Free, but donations accepted
I've always been impressed by the maze out in Burbank and this year's theme is the future, one year it was I think pigs taking revenge on humans or cannibals. It's quite long and an amazing build for someone's backyard.

4602 Morse Avenue, Sherman Oaks, CA 91432
October 17 & 18 – 6-10pm
Oct. 21-31 – 6-9pm weekdays, 6-10pm weekends
Free
More safe for the kiddies than a teenager out for a night of fun.
18727 Crenshaw Boulevard, Torrance CA 90504
Block Party is free; suggested donation for the walk-through maze is $5 (and a bargain at the price).
It's a ninja-themed horror maze, it just sound great coming of the tongue or writing it.
and check the rest over at Hollywood Gothique, which has the best list of home haunts.