But I don't want to pay more than 15% on top of btc price.
So you basically have to use exchanges outside AUS for not being charged +15%.
Or you have to use something like localbitcoins.
Buy them from someone else.
Although this method also introduces a premium
Nope, according to the guidance ..... the GST only apply to business tx. So localbitcoiners wont have to worry about double tax (otherwise, it would be impossible to enforce)
This guidance is so amusing, whoever came up with this dumbest idea should be shot.