I use this to find the best price near me.
Austin Gas Prices - Find Cheap Gas Prices in Texas
This one shows the average (and cost of crude) for what ever time duration you want to see (up to 6 years history). Also can do up to 3 locality price chart.
Historical Price Charts - Austin Gas Prices
It is amazing how the price fluctuates...especially when the gas companies were accused of gouging and how it suddenly dropped to almost 37% (see mid-late 2008).
How fast we forget
Note that the price of gas actually follow the crude price changes but about a week delayed (5-10 days).
I know this is for Texas but I believe they have it for different State as well.