Help Determining ARV on a Duplex in a Gentrifying area

[Charles Soper]

Comps are easy for SFR, but I'm currently looking at a duplex that needs a complete gut rehab in an gentrifying area of Sarasota. There are a few sold duplexes in the past few years but the closest one is area is over 18 months ago. I'm seeing numbers anywhere from the asking price on this one to 3X that and I'm a little frustrated trying to come up with a conservative ARV without way under or over estimating to the detriment of the cash I can have available for the rehab.

Anybody have a suggestion for how to comp out a small multi-family besides all the usual suspects like Zillow, Redfin, and Trulia (which haven't honestly been very helpful at all)?