If you're a family of 3 (2 adults and 1 child) and trying to find cheap Melbourne Aquarium tickets, here's a way to get your child's entry for just $2:
RedBalloon is selling the adult entries for $38 and children's for $22 each, but if you spend over $79 you will get $20 off using the "RBMEMBENAU" RedBalloon coupon. This would mean that you're effectively only paying $2 for your child's entry.
The total for your family would work out at $78, which is awesome as usually only families of 4 or single parents with 2 children get any sort of discount.
Right now no coupon pages such as Groupon or Scoopon are offering any deals on admissions and if you go buy the tickets directly from Melbourne Aquarium, even with their 20% off online saver offer, tickets for two adults and a child would work out at $85.60.
On the other hand, if you're planning to visit SeaLife in either 2 adults + 2 kids or a 1 adult + 2 kids setup, you're better off buying the online saver ticket bundles from Melbourne Aquarium directly.