I found a vegemite alternative that is actually 100% Australia called "Vege Spread", made by Freedom Foods.
They label their stuff well; anything vegan will be labelled vegan (in adition to dairy-free, egg-free, etc. for those looking out for allergies).
The Vege Spread is vegan, GMO/wheat/gluten/yeast free, and has Vitamin B complex and Folate (no B12 though).
I think it's going to take a bit to get used to; while similar to vegemite and marmite, it's definitely somewhat different.
285 grams is $4 (AU).