LAX
Santa Ana
Bob Hope
Long Beach
Ontario
cheapest flights will probably be at LAX tho being the biggest airport, the smaller ones usually have pricier tickets, but do some searching, you might come up with a deal. my suggestion is to go onto
www.kayak.com and put in LAX as your destination, but check the box that says "include nearby airports" and itll look for the best deal at all the surrounding ones.