Here's some proof that children don't need to have expensive stuff to be happy. I took my foster son to Upper Bidwell Park during our father-child bonding time yesterday. We spent about 45 minutes throwing rocks into the creek and walking around looking at the trees and such. He had a blast. My cost? $0.
Update: He was still asking me if we were going to throw rocks in the creek a month after we took this little excursion. Wow!