Congrats on the news. Isofix is not sold in Australia as it has not been recognised by Australian Standards because they will not pull their fingers out of their backsides and approve it. This does not mean it isn't as safe as our standards - it is better. In fact after 12 months, you do not even have to carry your child in a car seat in Oz according to law (but that is changing soon I believe).
I am ordering both an Isofix capsule and carseat from the UK next week as we are expecting soon and both the e92 and Subaru Liberty we own have Isofix as standard.
Going with:
Maxi-Cosi - Cabriofix- birth to 8 months or so
Maxi-Cosi Priorifix - 8 months plus
Best deal so far is from
www.lullabys.co.uk but shipping is steep so use an independent shipping agent like
www.excessbaggage.co.uk.