where to buy nxt!

Wow @lukoot well done and congrats for the fantastic progress to get this far by 30. There are a few threads currently discussing strategy options and decision making. I would suggest start reading this one…
https://www.propertyinvesting.com/topic/5019312-the-importance-of-having-a-strategy/
…and then do some work on your long term goals, plus think about the kind of investor you want to become. This will help with the “what to buy next” question. It really should fit into a bigger picture of what you want to achieve.
To answer the 2nd half of your Q re renos, subdivisions, and blocks of units, yes all of these are possible and affordable outside of Sydney. (I have a block of 3 under contract with a client currently, plus a small subdivision and dual occ etc) I would suggest don’t rush out to really distant rural at first, look for major regional and coastal markets whithin 3 hrs of Sydney for safety and to catch the natural ripple effect of capital gain that often happens at the tail end of the Sydney run, or else you could even consider SEQ as an alternate market. But again, you should work out what you want first, then pick the market to suit that.