One thing to consider is the fuels available to you. Because the LA is a bushed engine it needs a fuel with a fairly high proportion of castor for long life while the AX being ABN can survive with normal RC fuels but I'd still recommend a fuel with some castor in it.

You'll need to join a club and I found [link=http://www.cmac.org.au/default.htm]this one[/link] in Canberra but there's a link on their page to a [link=http://69.89.27.224/~monaromo/categories.php?category=Engines/Aircraft&page=1&sort=featured]hobby shop[/link] which seems to be in Canberra. The LA46 is $139 and the AX46 is $169 but have a look also at the ST GS45 which is $139, true ABC and every bit as good as an OS.