I tend to use my local model shop - rather surprisingly, many of the prices Iris charges as her normal RRP can be less than the discounted prices at some outlets. I don't know how it would compare to prices in Oz, but two or three mail order outlets I use in the UK, both for checking approximate retail prices and for some orders, might give you an idea. Hannant's have been established as a retail and mail order house since about 1910 (!), and their prices are normally a good indication of the average RRP. Another is Model Hobbies, who sell at a discount, with a flat rate of £3.30 for shipping in the UK. However, some prices can actually work out more, compared to my local shop! The Italeri 1/48th Boston I bought recently is advertised at £19.96 plus shipping at Model Hobbies, with the RRP shown as £24.96, which is roughly what Hannant's charge, plus shipping. My shop charged £16.99 !
The Aviation Hobby Shop don't charge for shipping in the UK, and charge at cost for overseas shipping. Their prices, again, are a good indication of the average RRP, but they do have some good deals, especially on out of production items. Where many outlets charge a premium because a kit is scarce, OOP or rare, TAHS are the opposite. As an example, one particular OOP 1/48th kit has a RRP of £24.99, and TAHS were selling for half price at £12.50, the equivalent of $25 Aus - that's a substantial amount!
I think it's a case of using such sites, either for info or purchase, then shopping around, not forgetting your local shop - it might prove less expensive overall.
