we asked the RAA about what they recomended and they said the old style s'n's capsule is still the safest for a newborn if your in an accident but they recomended not to leave bubs in there for more that 2hrs at a time.
when bubs exceeded the weight of the capsule at 9kgs they recomended the s'n's meridian ahr tilt and adjust which is birth to 4 years and bubs can face backward from 9-12kgs before being forward facing.
not sure about other states but in SA RAA and red cross hire out capsules for between $60-$80 depending if you want it for 3 or 6 months. you can also hire other car seats for bigger babies & kids from them but not sure on the costing.