Fuel Watch
Set up the e-mail advice for your local ( and surrounding suburbs ) you will get an e-mail about 3 pm ( +/- an hour ) will come with a warning when things in general are making a jump.
Can also do a trip plan. Put in the suburb or town where you are starting and where you are going and will give you a list of prices on the way.
Our local bp jumped to 154.9 Thursday an 5 min research paid 139.9 5 km away ( still about 5 bucks in front including driving there ).
Went to Bussleton Yesterday and already knew it was 146.9 down there so topped up rather than pay 154 when getting back to Perth.
Not worth driving all over town trying to get it but if you are going within a few kays of a servo that you know is cheep then it is worth stopping in.