What is the formula that you guys would use to calculate ROI and whether the investment was worth it?

NOI is a pre-tax calculation, which means all taxes are excluded from the formula.

You just have to find the right place and the numbers have to fit your formula.

Pay the bill yourself, then reimburse yourself by charging the tenants based on a formula.

I am using formulas found on BP and I understand they're just a baseline but it will take some time to learn how to squeeze those numbers depending on the deal. 

The formula is to buy a property so that the purchase price plus renovation costs do not exceed 70% of the ARV.

Aka .. formula for no cash flow 

There is only like 5-6 cities left that meet this formula. 

The XIRR and IRR functions in Excel are nearly identical besides one critical difference: ✔️ Timing Assumptions - - The IRR formula assumes there are equal time periods of a year between the cash flows of a project.

But on top of that do your own comps then who knows your comps might match up with your realtorsAs for you being worried about having to lower your ARV even more because of the market I would try my best to predict what could happen by using months of supply and the days on market formula...