" the government takes on every home produced --about 50% + of the cost is pure tax "
To my understanding, that figure must be the product of a hell of a lot of confusion. Apart from some import duties applicable to some items ( some imports are subject to exemptions or concessions under the existence of preference schemes) all materials including those imported plus all labour are subject only to GST, which is currently at 10%. In addition the GST tax is a value added tax, it only applies to what one charges net of costs (the value that has been added).
In addition to this tax there is a transaction tax called transfer duty based on the value of the property and applicable as follows: $ 430 plus $1.75 for every $100 over $31,000
