Newbie - ARV for a flip - reliable source for appraised value?

[Amit G.]

I know its suggested to approach a realtor or get an appraiser to determine the fair selling price of Real estate.  But as it has been mentioned in some of the other posts also, that it is not always feasible to approach these professionals for every property that you are trying to analyze, so my question here is how do you evaluate it at the beginning of the deal so you don't find yourself crossing your fingers at the time of appraisal while selling your property! 

So I am looking at a property that I can probably get for around 69k and straight out the bat, the zestimate for it is 184k.  I trust that it has a max rehab cost of 40k which I am going to know for sure the next weekend when I inspect the property with my GC.  Now my confusion lies with the fact that the nearby comps are nowhere near that zestimate and are averaging out to be around 110k. Now I also know that even though this property is currently zoned as Residential, it was zoned as Commercial before that and is also designed as a split. 

Do you think the flexibility with zoning justifies the higher zestimate?  Pardon my lack of understanding how zoning works!