I suggest getting as much as you can locally because the cost of shipping and import duty would probably eliminate any cost savings. Another reason is different countries use different threads. Try hardware stores or plumbing supplies.
Get a quote from Industrial Fittings in Brisbane (http://www.indfit.com/). They make a broad range of their own stuff (in both NPT and BSPT) as well as carry just about every type of fitting you’ll ever want.