It is a top/bottom style duplex with a flat roof and a basement so there should be no issues around ducting. each floor is around 1,100 sq ft  Any idea how much I should be looking to get this quoted for?  

The worst case scenario for me would be to just purchase rentals turnkey style. 

For garden style apartments, average OpEx was $5,661 per unit per year.

It depends on the age, construction, roof style, etc.

The plan (his plan) was to take the upstairs of a large, beautiful, historic building and convert it to 4 dorm style units.  

Finish your education, get established in a career with a couple of years of employment and use that time to live the most frugal life style possible to save up the cash needed for the necessary DP and reserves.

@Mark AndersonIt's a two way conversation.So, you should tell them what you are looking to do and the style of investing you want to work with. 

I have 15 years experience as a Project Manager building Multi- Family projects anywhere from 9 unit town homes, 200 mid rise projects, to 400 unit Garden Style developments on previously undeveloped land.

However, due to Prop 10 and peak purchase prices, I am considering to diversify to other areas and style of investments.

And the caps on a cottage style roof, and not sliding off with a 18' drop.