$80 seems pretty cheap to me when you consider an annual California State Park pass is $125. Kinda depends on which parks you visit most and how often if a pass is worth buying or not.
As Syd mentioned, the national and state parks have taken a serious beating during the recession... some have closed, others are being maintained by volunteers. Every time somebody buys a pass we are helping ensure their survival.
BTW, Death Valley is not supposed to be free... they just don't man the entrance gates all the time to check weather people paid or not.