Obviously websites like Zillow are big users of data to estimate a variety of things. 

For Example, if you estimate that one year's worth of reserves for a property is 15K and you save that much, do you take everything the property makes and move it to something else?

KORE Power, which was founded in 2018, said this would be the first lithium-ion battery manufacturing facility owned by a U.S. company.In addition to the 3,000 would-be KORE Power employees, the company estimated that the new plant would bring an additional 10,000 direct and indirect jobs to the selected region.

The estimate starts at $750. 

You should take each major item (roof, HVAC, exterior paint, etc) estimate replacement cost and lifetime and use that as Capex reserves.

Realtors make absurd claims about wholesalers being unethical because any homeowner has access to Zillow and can easily ascertain the estimated value of their house.

For each item that we felt was above and beyond what was immediately obvious from a walk through and would substantially affect our rehab budget, we included photos or excerpts from the inspection report, as well as an estimated cost for repair.

For my current opps I underwrite over 4K for just maintenance including turnover and deferred capex but that's how I estimate from fundamentals with 1.5 year avg turnover and I have learned never to take % of rent (you said quick math, so not holding you to it).Let me try this math:Let's do 3.5K * 12 = 42K ONLY maintenance and deferred capexInsurance = 10KProperty tax = 15K (hey it's TX)Rent = 725 * 12 *12 = 104.4KVacancy and overdue = 10%Pm + leasing + renewal = 9%Additional income = 6Kso Income before mortgage but after tax, insurance, vacancy, pm, maintenance and deferred capex = 24.5KLTV = 70%Loan amt = 840K * 1.01 (1 point origination)Interest = 4.5% (I don't think you can get 3.5% agency for 840K)Amortization = 30 yearsMonthly pmt = 4300First year Cf after mortgage = -19.34KTrue, he could have done enough work such that he can defer capex for a few years, and he can sell before he has to pay those capex, and maybe someone will price it poorly and not include that in their underwriting, and he can get away with it.

If the inspector gets out there and there's active termites, which they should tell you or your agent, you can likely add on the termite letter then (assuming they're an inspector who does the termite inspection as well).If you suspect other issues (ex: foundation), get the ball rolling on getting someone out for an estimate on repairs ASAP, so you have an idea what you're working with.

Being there's 1 vacant unit basically kills my cash flow until I get it rented( estimate 3-4 weeks to fill).