No sir, you are not.

You are under the same condition that many overseas people have, and that is expecting to see "price" not correctly stated, depending on many factors, none of which are clearly marked.

I have seen GST added TWICE from some american websites. Dont beat yourself up about it mate.

As answered elsewhere, prices for Australia are in USD and include GST so all-in are actually right around the same as you’d pay in the US (depending on your local sales tax)