How have you learned more about construction costs / rehab costs, and the best materials to use to make "renter proof", along with the 'what to look for' hidden expenses. 

I am preparing to start investing with the BRRR method. I am a commercial real estate broker so I understand the general market, comping out pricing, rents, structuring leases, finding deals, networking, etc. I have zero experience as a developer or general contractor.

What I really need to understand, and feel like the final piece that is holding me back, is the costs of rehabbing; how much does it cost to redo a kitchen- counters, cabinets, flooring, etc. What are the best materials that are quality, but keep a budget in mind, and "renter proof". 

I understand hands-on experience is the best teacher. I also understand it is all about simple math. The more accurate the math, and more predictable the returns and underwriting will be. I don't want to jump into something if I can't get an idea on these costs first.

I'd like to read a few books, and/or take an online class to help me understand the various costs of renovations, surprises/hidden costs to look out for, know the best materials to use for an ideal combination of quality but affordability, etc.

With some baseline understanding of these costs, I can start to underwrite light-to-mild fixer-uppers and get started with my first investment. Any recommendations are much appreciated.