500K+ would be sufficient for apartments.
Depends on what you want. I personally would target size - go for the larger ones ( they tend to be a bit older) with 2/3 bedrooms, 2 bathrooms and at least 1 car park ( for maximum appeal in the future). These would set you back above 600k, but are real value plays for the future as the brand new ones that offer the same size and utility are close to 1m ( if not more).
5 years back, melbourne was scarce of top quality apartments in its inner city. That has been ( or in the process of) being fixed by all the new ones that are high quality ( brand new). The 'high quality' comes with a price- see realestate.com.au for such listing such as prima pearl, etc...
So what about older ones that are a bit less quality ( however good enough) as compared to the brand new ones, and offer more on space and utility than the new ones? real bargains to be had....i think....with a bit of searching, you could snag a slighly older one with plenty of space and utility for 600k+. As the above poster said, i would then use the space to do capital improvements to increase the price appreciation. Tough to do if you opt for a showbox new one, unless you want to pay 1m and not bother with it in the first palce.