Nah, don't pay them that's the game!
I used to commute from Sydney to Melbourne regularly to visit customers. I never paid, and did so having learned it was only AU$10 fine (£4-5) if you got caught. Given there were never any ticket checkers, the easy part was to just jump off at a stop if you saw them getting on.
Melbournians are well versed in this game -- only tourists and overseas visitors and mugs pay on their system.