just stating the reality - there are whole apartment blocks using glass and windows in carlton from china, kitchens, floorboards, tiles etc.
Saving a couple of dollars for a sheet of glass yes but - say a bifold or stacking doors triple glazed is only 25% of the price what you would pay to the makers of the doors here. and that is delivered with insurance to your door which can be savings of 6-8K. Not everything can be imported unfortunately - as you mentioned but Unfortunately - that's how the game is played (which is why the harvey normans) are complainig why everyone is buying their electronics off the web.
Also - take a trip to your local bunnings - and you can easily work out majority of stuff is manufactured overseas anyway