To be honest best bang for your buck is still the age old icing sugar and flour mix with a bit of lure in it. 20kg flour bags are cheap so is bulk icing sugar and $50 worth or lure (cinnamon is nice and strong) will last you a bloody long time.
If you are trapping somewhere damp or in a wet area in the winter then a chew card nailed above the trap can provide both the visual and scent lure and can be reused plenty of times. The possum dough filled chew cards are better than the peanut butter filled ones. Higher chew rat for possums and the rats don't like them as much.
https://www.traps.co.nz/copy-of-chew-card-aniseed