This week? That depends on Australia Post, what you buy and where you buy it from.
Do you want a Corona style like a mincer which is hand operated, single roller like a Philmill 1, which can hook a drill up to or a double roller aka Barleycrusher, Valleymill style?
ESB in Sydney would have some Philmill 1 style. Check their webpage, send an email or make a call.
Goliath's in Adelaide would have a mill of some sort.
Grape and Grain in Melbourne would have a mill of some sort for sale, check their webpages.
As you are a Qld brewer, try the brewshop in Townsville, not sure of their name, something like the Brewer's Warehouse. I do not know what brewshops are in Brisbane or on the Goldcoast.
If you can wait longer, purchasing from overseas is an option. Maybe a local brewer would crush your grain for you in the interim. I bought a barleycrusher from the US. Took nearly three months to arrive, but am very happy with it. Also bought a cheap Bunnings drill to drive it with. With the way the exchange rate is at the moment, overseas purchases are attractive.
I'll sing the praise's of the margo mill it rocks, its cheap and availible in OZ pretty easily. It does the job as well as any other mill if the roller gap is set properly.
I got mine from brewmaker in adelaide on PH8369 3649.
also i have heard gaginis import them they are on 8346 5766 or 8346 1223.
One draw back is when motorized with a drill the rollers are quite loud but that is not really any big deal.
I bought my brewer modified one from Grumpies and it's a triple roller beauty at a fraction of the cost of the yank mills. Solid, heavy and well made, it made a great crush out of the German malts that I put through it last weekend - you can adjust the rollers to get a one pass crush on everything - even dry wheat!
They have adjusted the mill so you can have a wide range of gap settings and it comes with a modified hopper and a drill bit so you can hook up the mill to your drill for quicker crushes. Grab some MDF and a few screws, cut a hole in the MDF with a jigsaw, mount the mill on the MDF over the hole and voila you have a grain mill that crushes straight into the grain pail below.
Save yourself the hassle, cost and wait time with US postage and get a Margo mill here in Oz.