The obvious other choice is to tap into equity and go for BRRRR-like method repeatedly. $500 is a tall order to find, true net in this market, for quality neighborhoods. 

Use the BRRR method and self manage for as long as you can.

You'll have to put in a lot of work either way, but his method will require fewer dollars out of your pocket up front.

Now that my personal finances are in better shape, I plan to open a taxable brokerage account and use gains generated in the stock market as additional capital to invest in real estate.My primary interests include long term, buy and hold strategies; real estate financing methods; single family and small to medium multi-unit properties; and property management.

@Michael S Dawson  A cost segregation study is a very complex and calculation intensive process when done right with a quality engineering-based method.

That's the simple, proven method that leads to success.

Products and technology change constantly and a lot of pros fail to adjust their methods to meet new specs.  

My method to determine this is to do a manual comp analysis of properties on Airbnb and Furnished Finder.

Still $25k now and the additional $75k 30 years from now, just different methods.

My previous method was almost the same BC the locks are expensive.