Disneyland raises their prices right before summer. The cycle is, they offer discounts from Jan 1 through the end of May, right before Memorial day, then up the prices to coincide with their heavy visitor season, summer, and stop the discounts. There were discount "hopper" (this would allow you to visit Disneyland and California Adventure) tickets available for use through the end of May, and some supermarkets were selling the gift cards to purchase them. Not sure if they did this everywhere but a friend of mine checked last week for some for her family who will be visiting in 2 weeks, and the store had pulled the cards. If you know anyone here in SoCal you could have them check for you, as they were specifically for SoCal residents, but if I recall correctly they stated on the card they were for use through about the end of May.
Another option that just came to mind, if you're staying in a hotel you may be able to get tix through them at a discount so you might want to check there.
Otherwise Costco or AAA will be your best bet.