From their site:
For just $99 your FAMILY can enjoy great exhibitions, holiday activities and more until 30 June 2015. That's right, 18 months of free general entry to the Powerhouse Museum and Powerhouse Discovery Centre, and exclusive discounts at Sydney Observatory, for less than the price of a one year family membership. Plus visit Game Masters the exhibition again and again for free (from 13 December). Hurry, this offer won't last!
This is a household membership, for two adults and all students up to 18 at the same address.
Consider one off family tickets to following venues which are FREE with this membership for 18months:
Powerhouse $30
Questacon (ACT) $70
Sydney Observatory (Day Visit) $22
see reciprocal benefits for more info on venues in other states: http://www.powerhousemuseum.com/pdf/members/reciprocal_benef…
Reasonable deal for 18 months membership though Museum Victoria normal price for 12 months is $70 per household and gives you reciprocal entry to Powerhouse, Questacon etc…
https://museumvictoria.com.au/about/members/online-membershi…