|"I have a real PC it will cost me NZ$2600 to upgrade it"|
Either NZ prices are way out of whack, or you're shopping at the wrong places, or your system is extremely outdated.
"I haven't bought it yet"
Then don't do it! The "all-in-one" is nothing more than a laptop without the portability. And just like a laptop, it has very little upgradability. Get a PC with a tower than can be upgraded.