Don't know about that ap you are using but petrolspy.com.au seems to clearly show all the brands and prices. Today there is about a 20c range from lowest to highest. Bowenville one of the cheapest.20c range in Dalby? Nah, unleaded 91 ranges from 141.7 to 147.9 (as per petrolspy and my own observations confirm). Bowenville 139.9, but I wouldn't drive a ~60km round trip to save 1.8c/l! If I was going eastwards I'd fill up in Toowoomba and save 9.8c/l.
Interesting that since the Toowoomba bypass has opened, the servos at Charlton have raised their prices, currently 150.9. What a ripoff!