If your father lives in So. Cal, have him look for coupons in the local paper or other places. They sometimes run a "buy the adult/get the kid free" deal. Or the local Entertainment Book porbably has a coupon, fi there are other coupons you would use. It's not cheap, but it's a lot of fun.
As the PP mentioned, the food isn't terribly kid-friendly and there is no kids menu. If your kids won't eat what they list on the website, I'd recommend bringing a sandwich or something. They will let you bring in anything except your own alcohol.
We may try the Pirate Adventure this summer and could then compare.
PHXscuba