I don't know about where you live but where I am they change the price about 4 times a day at 6am, 12pm, 6pm, and 12am. Aren't the prices going to sky-rocket because of the hurricain taking 25% of the US oil production?

Check out shells website for info on when to buy, they usually tell you when it's about to go up and have the prices of all their stations.

[australian site link] http://www.shell.com/home/au-en/html/iwgen/shell_for_motorists/petrol_pricing/price_search/app_price_search_0221.html