Here are GasBuddy average gas prices:
http://then.gasbuddy.com/GB_Price_List.aspx
This is relative, since they don't have average diesel prices. Nevada, Oregon, Washington, and California are in the bottom 5 (i.e. highest prices), with Oregon
average $0.25 cheaper than CA. Is it enough more to keep me out of CA? No, but I make every effort to avoid filling up in CA. Not because of the money as much as the politics.