Hi Sm,

I recently had builders tender for a two-level apartment building for about $1900/m2 with low-medium level finish, and a bit of "polish" to the entry lobby.  It had a basement carpark which came back at about $700/m2.  So you're not too far off the mark.
 
Then again, use averages just as a ball-park guide as averages can be misleading due to too many parameters e.g. site constraints, access, size of development, etc.

My experience with developer-type clients have revealed that one would usually work from both "ends" to achieve the required yield and economic feasibility – the cost-driven approach (As above), as well as the market-driven approach to determine the typology and mix of apartments appropriate for the area.  The two approaches usually meet somewhere in between which determines your yield outcomes.  Seek opinions from real-estate experts and do your own research.

Using an architect will add value to your project (I'm slightly biased here! ), and fees vary (loosely a percentage of construction costs to fixed fees) depending on scope of services – full services – from sketch design, town-planning to documentation and administration.