Quote from @Jaycee Greene: Assuming you pay asking price, I'd estimate the down payment for something like that using a hard money loan (HML) would be around 40% of the purchase price and your monthly payment would be $2,600 with an interest rate in the low 7% range (probably need a 700+ credit score to get that).

We can buy the house for maybe 125k and he estimates 120k in renovations.

No management costs as it would be self managed, and estimated property taxes by the average of the past few years.

Its current projections are to bring in between 150k and 180k with estimated costs of 60k.  

These methods include: Detailed Engineering Cost ApproachDetailed Engineering Cost Estimate ApproachSurvey or Letter ApproachResidual Estimation ApproachSampling or Modeling ApproachExperience or “Rule of Thumb” ApproachIt’s important to understand the differences between the approaches including which one best fits your property and the reliability of each approach.DETAILED ENGINEERING COST APPROACHThis approach compiles the costs from construction and accounting reports to build a report.

Compare other rentals with a similar size, location and bedroom count to get an estimate of what the rent would be while you're living there.

Airdna will give you a good estimate of the demand for the area.

You can use this tool to estimate future property taxes: https://treas-secure.state.mi.us/ptestimator/ptestimator.asp

Price out as much as you can in terms of materials and estimates.

Quote from @Mike Sfera: for a duplex, is the BP rent estimate for per unit of combined?