This is the most-searched version of the question, whether you're looking in NSW, Queensland, Victoria or WA, and the answer is the same everywhere: a full ensuite under $30,000 means a used mid-size van, roughly 8 to 15 years old. That vintage is where full bathrooms became standard kit, and where depreciation has done enough work to bring them into range.
Go in with your eyes open about what that age means: a three-way fridge and hot water system near the end of their lives, batteries that are a cost rather than a feature, tyres that have aged out regardless of tread, and quite possibly a resealing history around the roof and windows. None of that is a dealbreaker - it's a negotiating list.
What is a dealbreaker is water damage. It's the number one thing that turns a used bargain into a write-off, and at this age bracket you must assume it's present until you've proven otherwise: push on the walls around every window and hatch, walk the whole floor, smell the van closed up, and treat fresh sealant lines as a question that needs a good answer. And before any money moves, spend the $2 on a PPSR search - if the seller still owes money on the van, the finance company can repossess it from you.