Its good to buy Australian made if its world class.
But remember, there is often an imported content in any Australian made product.
And of course, if the Australian owner of that business then goes out and buys a plasma telly with your mark-up then the money ends up offshore anyway (less the margin for the Australian retailer of the telly). So your ability to influence matters is marginal (albeit not in vain, don't get me wrong, just marginal).
At the end of the day, our combined marginal propensity to consume imports as a nation is pretty fixed, and feeds into the 'multiiplier' identity (see
en.wikipedia.org/wiki/Spending_multiplier).
Finally, lets not 'crowd out' the things we do best, like making wine, or designing things (even if they are made overseas), by 'protecting' second rate products. That way, we all get the gains from trade.
So choose the best product for your need - hopefully its got a high proportion of Australian value add. If not, vote with your $, and don't feel too guilty about it!