I assume there are a lot of variables here that may make this difficult to answer.

Seems very variable right?

- After all of these variables are factored in, find out if the Cap Rate of the subject building with the rental income provided is close to the local market performance or way below. 

I bet the answer would be solving some sort of multi-variable differential equation with the interest rate of the financing, your cap rate, tax bracket that you are in, inflation rate, ...

@Samantha Mosquera It’s always price.If my flips are not getting on average one viewing a day, I’ll drop the price at least 5%, sometimes up to 10% within a week.I’ll repeat this process until either I get a good cadence of views and now I’m looking for one offer for every ten views, or until I decide it would make more sense for me to refi out and rent it.You’ve controlled the variables that you can control.

There are two other variables that could improve cash flow. 

But thats not the only thing one should look at as there are other variables involved when calculating profitability.

All of the information necessary to capture all of the variables and issues in seller financing would easily be volumes, not a "booklet".

I’m a veterinarian and qualify for a few ‘doctors loans’ which have 0% down, no PMI, but variable interest rates.

This is from the bit of research I've done, but I'm sure there are other variables.