It's substantially cheaper than buying a comparable single family home. 

How much did it cost, and how was the process compared to a standard mortgage?

Those numbers look good on paper compared to your 450K home, but I'm sure my west-side homes offer 3 times the stress!

You need to examine the details of your comparables to determine what the potential ARV is:Are the comparables all in the same city or village Sometimes using the radius for comparison results in spillover from another city or village into the comparables.  

In fact, it's the person you should be trying to pay more.This is the guy who brings you deals or sells your property. 1-2% on a property is nothing compared to how energized your realtor will be for you.So you knock his commission down, do you really think he'll bring you the next deal he sees?

How does that compare to a triplex? 

"Compared to what?"  

I work up a basic rehab and a nice rehab figure and compare those to my ranges.

As far as comparable rentals go, there is another slightly better property for sale for $225,000 with 3 units right across from the hospital (not far from the other duplex location). 2 legal suites and one illegal suite with potential to make another illegal suite.

I personally rent a place with Formica countertops and older carpet (needs to be stretched) because it saved us at least $400 a month on rent compared to the places that have been updated more recently.