I am in Oz 2 and am glad I purchased my refurb i5 iMac (perfect in every way - just like new) several weeks ago. The Australian dollar has lost a bit of ground and if keeps going down there will most certainly be a price increase next time round. If our dollar really tanks it the price could really jump up

A good example of this would be when my Missus bought her MacBook a couple of years ago (1st All Aluminum Unibody Model - same place in the product line as the current 13" MacBook Pro) it cost her $2100 (Australian Dollar was very weak then) the current equivalent 13" MacBook Pro in Australia costs $1499 (due to our strong dollar at the time of its release) My advice to you would be to grab an iMac now while the current price is neither extortive or prohibitive.
I managed to get my iMac in the end for 25% off the new price, grab yourself a deal on a refurb you'll be glad you did...
http://store.apple.com/au/browse/home/specialdeals/mac?mco=OTY2ODY3Nw