seriously, i paid $250 for my pivots. skiing isn't cheap and i understand you may not have the means to buy sufficient gear. But don't start ghetto rigging your skis, you just gonna either fuck yourself over from an unexpected injury, or ruin your equipment.
save up and get some REAL bindings made for REAL skiing on REAL snow.
PX12's are like $120, and I'm sure there is a shop local in Australia that will have some springtime deals. Rental bindings are terrible, and used for rentals for a reason.