Your request is too broad. are you interested in the maintenance of commercial/multi family, the management of tenants, the sourcing of properties, the leasing of properties, the disposition of them, the building of them, the design?

online resources shows all variety with huge range, so is there any reliable source where I can check most updated rates as of current day ?

Can you source tenants yourself?

Based on your post, I've bolded the titles below that should be most applicable to assisting with estimating costs.For 5+ Multifamily/Commercial in General:Crushing It in Apartments and Commercial Real Estate by Brian Murray - Great Source of InfoThe How to Add Value Handbook for Commercial Real Estate by Brian HennessyThe Due Diligence Handbook for Commercial Real Estate by Brian HennessyFor Large Multifamily and Apartment Syndication the following are recommended :Wheelbarrow Profits by Jake and Gino - Simple, Easy to Read as a good intro.Best Ever Real Estate Syndication Book by Joe Fairless - Detailed, Lot of Information, RecommendedIt's a Whole New Business by Gene Trowbridge - Detailed, ThoroughAdditionally, the "Book on Estimating Rehab Costs" by J.

LOLMy thread was going to start here and hopefully it would work from there, I'm sure BP has this one already, but will post it anyways.https://www.whitehouse.gov/And the link to my statehttps://www.wisconsin.gov/Pages/Home.aspxPersonally I find the information that has been offered so far from pretty much all sources has been vague and leaves a lot of questions.

You’ve lost your primary source of income and are unsure if you’ll be able to pay rent next month.

Hello fellow BPers,I was wondering if anyone has a really solid, good email template to send to real estate agents and brokers sourcing deals and starting a relationship.

Kenneth's answer is the best for this situation and borrowing from private sources as well. 

It’s free and aggregates information from a handful of public record sources.

They seem to ignore the fact that most of these sources told them to start by building a team.I think no matter where you are getting your strategy from, the first step should always be to build a strong team.