I don't know the exact pricing but the 34K mile Global Explorer was priced to be similar to the 4-continent OWE fare, with the various Circle fares being somewhat cheaper. You should be able to use the 29K mile circle fare (the cheapest offered); I'm guessing AUD 8-9K but I haven't checked. Any full-service travel agency can look up these fares for you, surely there are some in Perth? I've used http://www.travel.co.nz in AKL and they were quite good at RTW fares including giving quotes by email (but NZ/Australia fares are now higher than US-origin, at the time they were 20%+ lower).