If you plan to visit for more than a day, you can save money by buying two- three-, four-, and five-day Park Hopper tickets that grant same-day "hopping" privileges between Disneyland and Disney’s California Adventure. You get a discount on the multiple-day passes if you buy online through the Disneyland website.
A one-day Park Hopper pass costs $137 for anyone 10 or older, $131 for kids ages 3–9. Admission to either park (but not both) is $92 or $86 for kids 3–9; kids 2 and under are free.
In addition to tickets, parking is $16–$22 (unless your hotel has a shuttle or is within walking distance), and meals in the parks and at Downtown Disney range from $10 to $30 per person.