Howdy @Kyle Neff
For me there are several stages in evaluating a BRRRR deal.
1. To find good deals you have to look at lots and lots of properties (on paper/computer) to find a few to go through an initial screening. Having a good "Investor friendly " Realtor can be a big help to that process. You need to establish your investment goals. Then determine what criteria you want potential properties to meet (i.e. SFR or Multi family, 1% rule, minimum of $100 per unit/month cash flow, minimum 10% CCR ... ). If they do not meet your criteria don't waste your time looking at them.
2. Once you find properties that meet your criteria you can do a generic analysis of the property. Determine a good ARV (use your Realtor). If you can, estimate how much Rehab is needed (based on the pictures). Add an additional 15% to your estimate because it's never right. Most of my deals require significant Rehabs. No cosmetic jobs. You can use the 50% Rule for the initial Cash Flow analysis. It will provide you a conservative view of the deal. If the analysis provides a positive report then a more detailed look is warranted.
3. Conduct a detailed analysis. Get prequalified for the Refinance loan so you know what terms and rates you should have. Visit the property with your Realtor and a General Contractor, if you have one. Take lots of pictures. Get as much details and documentation from the Seller as possible for your Analysis. Get a quote from an insurance agent. Contact the local utility companies. This is how you get the accurate data you are asking about.
4. If everything looks good then determine your Maximum Allowable Offer (MAO). ARV x 75% (Lender LTV) - Rehab Estimate - Closing Costs - Holding Costs = MAO. This MAO is what the Purchase price must not go over "if" you want 100% of your costs (Aquisition Loan and your cash) back. This will rarely be the same as the Sellers Asking price. You will get a lot of "No's".
Obviously, the Purchase price is negotiable. You will not always be able to get 100% of your cash back. You have to determine if is an acceptable amount because of the Cash Flow.
Hope this helps.