You are correct, that this has long been the conventional figure used to estimate cost for buildable sf in NYC. 

I have already sold over 50 lots in 2021 and have approximately 90 listed for sale. 

Please also make sure how much points or cost you are paying by looking at the Loan Estimate.

Depending on your estimate of the ARV and the ability to raise the rent on the 1BR, this looks like a "lendable" deal, IMO. 

I know very well all the models of house they build, so can give you an accurate estimate and guide you thru the process.Steve

Please also make sure how much points or cost you are paying by looking at the Loan Estimate.

Quote from @Travis Timmons: @Jay Hinrichs this is an educated guess, but I think the market rent for our property unfurnished, long term would be approximately $1100 per month and we have rented it for $1600 per month as a furnished, medium term rental.  

Look at before and after pics and real estate listings for a flip and estimate what work they did and what it would cost you.

I was holding approximately 20 of their properties at that time, so you can imagine that unexpectedly paying out 20 interest payments every month was impossible.   

For flipping, focus on accurate ARV estimates and budgeting for unexpected costs, while for BRRRR, building strong relationships with local lenders that can help streamline your hard money into your refinancing.