How to evaluate the cost of building in a market for underwriting

[Jesse Fernandez]

Hi all, I will like to underwrite a potential multifamily deal in a secondary market and would like to factor in the cost of building for a similar unit to understand if I am overpaying or underpaying. I know there are also many other variables to factor in but I'm just interested in this aspect for now. 

My questions are:

1. What sources are out there to know the cost of building (ie, for a 1br/1bth X sq ft)

2. What is the ratio to consider it a win in terms of what it costs to build-to- what I will pay for a unit?