Unfortunately Australian dealers don't have the option of avoiding GST, so we will always be more expensive than buying through foreign suppliers.
I'm looking forward to the day Customs reduces the duty free threshold for imports to below $1000, as this will mean people who buy from overseas will have an extra ~16% to pay (GST plus Duty), which will make it easier for Aussie dealers to stay afloat.
This is the same problem that means Kogan can avoid paying GST & duty on its sub $1000 sales, as they ship direct from China.
Given the amount of R&D and such that goes into Borla, I think they are quite reasonably priced. There are cheaper options around, and if you cant afford Borla, then go for the cheaper brands... But don't expect the same levels of testing and quality.
We've been around for 7 years now, and have been selling Mustang systems all that time.
M