For multi-family units with 4 or less units it is still considered a single family and you can use the usual comps comparison approach and find similar properties in the area.For multi-family units with 5 or more they are considered commercial and the process or rules for determining value are greatly different.

Then look at the cost of some of the major repairs that may need to be performed. 55% is a good Estimate but you'll want to look at all the real data before making a hard comparison.

And one effect of the "luxury apartment" boom is that it starts making higher rents elsewhere seem reasonable in comparison.

Those are the two major players when trying to make an apples to apples comparison of debt vs no debt.A better question for what you are looking for would be: will an all cash purchase or a leveraged purchase yield a larger return?

It got me wondering about the logistics around establishing a partnership, specifically the sequence of events.

Professional services are generally valued based on expertise, knowledge, length of time they have practiced, success rates in comparison to similar alternative services.

Direct sales comparison is the way to go. 

I am trying to find some hard data on such things as square foot costs, permit requirements when building out of state and scheduling comparisons.  

With that in hand, you can compare similar existing units and determine rent comparisons to have a credible feasibility plan for your lender.

At least a few years ago, the cap on section 8 was pretty low in comparison to market rate for where our building was located.