If I can buy it here in Australia, then I do. We have a variety of good suppliers and I have generally found the service to be excellent.
If I can't buy the specific item here in Australia, then I am more than happy to purchase from OS, and have also had great outcomes.
Buying goods from OS (or the grey market) that can be purchased through legitimate distributors here is counter productive. We complain local suppliers are more expensive, but by making it a smaller and smaller market, we guarantee it will never get better. And at the same time we ask them to donate goods and sponsor events!
Second hand is another thing, and one I've used very successfully (buying and selling) here on IIS.
Just my 2.08 US cents!