As for rents, I have received the same estimates from 4 sources so hopefully it’s accurate but I guess we will see.

Yet, there are so many online platforms such as Trulia heatmaps, Redfin, Eppraisal, Zillow, etc. to estimate what the Median Price Range is for a given market's city...so if finding this info online is feasible in that regard, where can I find it and which is most accurate? 

They're very in depth and accurate and you could even argue that they give away our secrets, right?

They identifiy the "good ones" for the investor by visiting the property, preparing an accurate rehab estimate, pulling accurate market comps and market rent rates, utilize their REO broker contacts, etc.There's a little bit of fatigue and time restrictions on the part of investors who are trying to process numerous new REOs hitting the market every day (often folks who have regular jobs), so there is definitely a role for a good intermediary that is worth a fee.

It makes you dependent on those assessed values being accurate and in my area they can vary widely for similar properties.Assumming the govt is efficient is dangerous.Over many properties, the averages might work out, but the problem is that you are going to try to cherry pick the "best" deals where the values diverge the most.

Two resources we've found to be invaluable are:www.truecredit.comwww.creditchecktotal.comOur company offers a myriad of various different types of loans and financial services, and we find these sites provide the most accurate scores when compared with the information seen by and at the big banks (Wells Fargo, B of A, Citi, Chase, etc.) when they do a hard credit pull on an applicant.

Not 100% reliable, but probably accurate in this case.

It is a quick and dirty method, if done accurately, to indicate whether or not the purchase price supports an investment likely to provide a positive cash flow over a long term holding period.

Because other aspects of my business(es) will have great impact on my tax bracket, available deductions, etc, I'm not sure I could accurately factor taxes into the equation even if I wanted to.

You must have an experienced individual run through the property and give an accurate estimate of repairs (and it must be based on the exit strategy, ie. if a retail flip, then rehab should be based on that, if a buy and hold exit to a landlord, then rehab based on that quality)