Okay, i just got back from Costco. It shows how different stores seem to carry different things.
My Costco in Vista has the:
So.Cal Disneyland tickets (4 days, 1 park each day, or use it as a 2 day park hopper) for $119
They also carry children's/senior 1 day LegoLand admission $29.99
no residency restriction.
SeaWorld Silver Passports (an annual pass) Adults: $67.89 Children $55.79no residency restrictions.
They may also have Wild Animal Park / San Diego Zoo tickets, but they were not displayed.
I hope this helps.
Have a great trip!