That amount is negotiable and will vary according to a variety of factors:  the value of the property; the motivation of the homeowner; your negotiating skills, etc. 

Let the tenant pay down the mortgage to increase equity and market appreciation to factor in.

What factors should I be looking at?

A lot of investors think that they cycle will go so well that it will eliminate their personal debt, but when you keep adding more debt to the calculation and factor in the likelihood and reality that more properties equal more problems, it's not realistic to think this way.

Cap rates will adjust from market to market based on a number of factors that have already been brought up by others.

(A) Before utilities and (B) After utilities.OR you do your own due diligence inspection before utilities, then professional inspection After utilities.But most of all, factor potential electrical and plumbing issues into your purchase price. electrical problems

In fact, most of what I hear is that tax benefits should just be viewed as extra benefits, not the determining factor in a deal analysis.

I spoke with a property manager and they confirmed my 5% vacancy factor.  

When you do the complete underwriting though and are familiar with the area, you can factor in any value-add opportunities, financing available (this is big) gentrification etc.

That's a computer program designed to review comparable properties in the location by a variety of factors in order to determine what the value is.