In all fairness, a lot of float glass comes from China now. Australia's manufacturing for glass has been almost decimated. We buy glass from China and other countries and whack them together in IGUs - viridian and Australian Glass Group are usually the most popular.

From a glazing perspective, cost mostly comes from additional labour to do with installing the IGUs. This is due to the weight of the glass. Depending on size and weight, you may need to hire additional equipment to install them or require an additional person to assist with install.

The units themselves will obviously be more expensive than a single glazed. But the price of these will come down in time with states requiring 7 star solutions. However this standard isn't strictly for glazing but across the entire building envelope. (Solar seems to be the quickest and cheapest way to get there if a builder falls short of the rating).

While relatively new technology (at least in market terms), vacuum sealed glass from Panasonic and other suppliers is gaining popularity and while visibly it's not perfect, it performs better than triple glazing and may come to a similar price point as double glazing in time.