For example, if your current single family home was worth $200,000 then multiply it by 80% = $160,000.  

Multiply the average cost/square foot by the square footage of your subject property then subtract 10-20% to be conservative. 

However I do have approx. 250K investments, which I am intended to use and multiply and achieve my American dream.

Terms like "Return on investment", "Return of Investment", "Capitalization Rate", "Gross Multiplier", "50% rule" (although I like the 49% rule), etc.... need to be learned and understood.This site is invaluable for learning all this and more.So, to answer your question "won't the deals dry up", I answer, only if the United States becomes a totally Socialist Republic where no one can own any land.

I prefer to use the average selling cost per square foot and multiply that by the square footage of the subject property to determine the FMV.Note:  Whenever possible, I try to get 5 comps for any property I'm working on.  

Multiply the monthly net rent by 12 & divide by the as is value of the property minus expenses you would have if you sold. 

Multiply that by 0.9 to get max total loan.

Appraisals are so subjective and are not always accurate, you have to look at the comps they pulled and whether they included a gross rents multiplier since this is an investment property.

We are looking for rental investments in the Cincinnati area and are hoping to apply the BRRRR strategy to make our properties multiply down the road. 

I've been able to find several areas where my properties have multiplied in value quickly, but I'm sure not every deal here is so great.