I didn't recommend that the OP buy a GTX 1070, although it would be a better deal at $379 than a $300+ R9 380X at this stage of the game. The OP does need something now though, so R9 380X isn't bad.
Personally I would just go with an R9 390X and be set for a good long while if I had to buy AMD and had to buy right now.
$379 US will magically turn into $500 AUD here. And on the 380s/390s, are there any driver issues? Looks like the 380s suffered black screen issues and driver crashes over the past few months.