(Ever heard the saying "beating a dead horse"). 

This is a spherical horse in vacuum or the 'efficient market' which does not exist (hence all last Nobel prizes are about behavioral economics) .

Horse hair plaster pulling away from walls and ceilings, knob & tube, tons of trim needing repair, kitchen and bath from the 1930s, plus it needed a new septic.  

If you have to do financial wrangling or horse trading to make it happen at some point you may be in a position where you may struggle mightily to make ends meet.

Again, not trying to be rude or anything, but I think you're putting the cart before the horse.   

@Lue Brooks sounds like you may have put the cart before the horse on this one.

As they say you can lead a horse to water.........

An emotional support animal letter for a mini horse 

Carleton and Ottawa had a bit of a rivalry when I was attending and one of the chants toward Ottawa U was making fun of the Gee Gee (which I have since learned is the first horse out of the gates in a horse race). 

(It sounds ridiculous, and it is, but I've heard that one straight from the horse's mouth of a local city building department in RI.)My usual advice on that is, make sure the property makes sense on its own, and that you want to do the deal regardless of whether your value-add (subdivide-and-build in this case) strategy works, and then if it happens to work consider that extra/gravy.Another option if you don't get a response here is to investigate RS Means as that's a company that has been around a long time and specifically exists to provide the kind of per-sq-ft building cost you're asking about.