Do bunnings still rent their utes cheaply? I can remember seeing they were something like $35 for a half day at some point - although this could of been a while back and no doubt had conditions..............maybe try a few of the smaller players in the rental car game, we recently changed who we always rented vehicles off at work and are saving around 40% on what we use to pay and thats without having to set up accounts, just using a cc when we need a vehicle for a day or so.
Bunnings Ute rates are good but you can't book them in advance and they don't have many vehicles. Also my nearest Bunnings is a $20 taxi ride away whereas it's only $15 to Waterloo where Sydney Ute rentals are based or I can cycle there in 20 mins.