I would be cautious using comp information from zillow.com because basically zillow takes the average selling price per square foot of an area and multiplies it by the square feet of the house to come up with their Zestimate.  

It's all about the assessed value and the tax multiplier which could increase depending on things like new tax referendums or tax hikes. 

However, if you want to do more than one, you can multiply your money by getting a loan.

If you do your losses will multiply and a nonpaying tenant will still be resident in your unit.

Take the percentage above, multiply it by the BASE loan amount (the original loan amount without the up front MIP added back in) and divide by 12.

I would say atleast 10k or use the loan amount and multiply it by 5%.

So taking into account part of that 1200 each month has to go to at least insurance and property taxes your break even time gets extended even further out.If you use a mortgage you are taking money from a bank to buy a property that the tenants will then pay off the mortgage.Another way of looking at this:Lets say all things are equal and you end up holding this property for 30 years and you never have a single expense and you pocket all the cash:A 30 mortgage at 5% with 30k down will cost you $483 per month for 360 monthsso if you pocket the excess each month you will have (1200-483)=717 per month x by 360 months gets you $258,000 for only a 30k investmentnow take that number and multiply by 4 because with 30k down you can buy 4 properties and you have $1,032,480so 120K = $1,032480Your way will pocket 1200 per month for 360 months = $432,000so 120k=$432,000 at the end of 30 yearsnow of course there are extra costs included with the above calculations and thats where owning multiple properties spreads out your risk.  

This has happened multiply times. 

If this isn’t an option, research snow removal/cutting tools, such as the Avalanche or Roof Razor, that are designed to protect you and your roof shingles.

ARV multiplied by .70 (seventy percent) minus repairs = Maximum Allowable Offer.So in your case above I would go conservative and use the low end of your range to be safe:$165,000 x .70 - 20,000 = $95,500So, at first sniff your offer of $86,000 would work.Now, make SURE that your estimated repairs are accurate.