you can read for free if you have Kindle Unlimited.He also has the syndicated deal analyzer tool (for purchase) and a forum and a bunch of videos to help you learn the process.I'd also say best way to estimate expenses is to look at a whole lot of deals. 

It was almost a turn-key and has increased in value significantly (thank you path of progress).

They all tripled in value by 1986 when the market started to crash.

I am curious to know if anyone has recommendations regarding which tools to use for estimating rental rates for investment properties.

It just got appraised and went up $75k in value! 

As the town appreciates in value and gentrification takes place, at some point these city lots very close to the main street will become too valuable for a mobile home.  

Finally, BP has various tools available to help you analyze your deals (rental, flips, wholesale, etc), feel free to use them: https://www.biggerpockets.com/investment-calculators Please let me know if I can help, and best of luck!

They are a nice little tool to give you a quick method to calculate cash flow on a property, while also being fairly inclusive of the expenses. 

However real estate and gold can fall in value but usually not as fast as stocks/equities and interest rates. 

As I think of all of them tools in a toolbox.