What's the song the house don't fall when the bones are good?

The calculator seems to mark it down to some scientific formula, but what we're really trying to do is put all the numbers involved in owning real estate down into a usable format.For example, what goes into owning or buying a property? 

That's the the formula. 

Songs like the only realistic option on this is a short sale, but that heavily depends on what the seller means by selling for $50k.

Is there some type of formula to guesstimate?

I'm sure the lower mobility patterns of the boomers is baked into the formula.

But I'm wondering if their formula even applies to this market since according to Airbnb most people are booking more than 30 days out for the Smokies?

Does anyone know of a formula to calculate (Guesstimate really) the current balance assuming the mortgage is currently delinquent?  

@Jonathan Greene, @Hui Song - I checked with the zoning office, this is a non conforming 3 family unit. 

It's easy to see what investors are paying for properties but I need a better fine tuned formula for the Philly market.