Well being in Australia the kits are going to be more expensive. Projector headlights are supposed to be better then the normal headlight. Look at the brand new BMWs as they all have projector and ellipsoid headlights. Their are angel eye kits that include just the rings and wiring and you install then yourself. Those are a lot cheaper then buying new headlights. The thing is their are do many knockoffs out their that the quality can be very very low. Only ZKW or Bosch headlights are true European OEM headlights with the glass lense but their about $609-700 US.
If your interested in the angel eye kit where you install then yourself you have to open the headlight by baking it in the oven at 180C for around 15 mins to seperatley the cover from the housing. If your good with wiring I'd say go for it. Stock headlights go for pretty cheap if you accidentally break something.