I would've like to make my case of being grandfathered in for the simple fact that the previous owner (whom is close to 80 years of age and self managed as Owner Occupied for over 35 years) had tried in the past:  1st - To reduce taxes because it's listed as a 3 & 2 but then the tax site has it as 6+ and when the old man had them visit the buildings they seen 7 mailboxes that USPS installed( so he decided to stay shut and not pursue it) 2nd- The 2 family already had 3 gas meters and even a fire escape because the 3rd floor studio apartment only has access thru back door.The front building has 4 gas meters, 1st floor, 2nd floor, 3rd floor and one for the front Studio apartment (which is like a basement apartment) but its street level with main entrance off sidewalk. 

They may work great, or you may be better off just pre-printing a simple letter and taping it (with blue painter's tape) to the front door knob.  

1) Buy real estate.2) Hold on3) Grow rich.It really is that simple. 

Straight and simple to reach your goal of $4k cash flow should be as many doors as $250k can get you.

@Ben Carlson An issue that might seem like a simple one is access.

Now, this is a very simple approach, but it gives the high level view.

In simple terms, the entire cost to the REI is only what cash that comes out of their pockets.

If you're just starting out, you can use something as simple as Excel or google sheets to keep track of income and expenditures.

Simple as that. 

I would offer to cover part of the internet expense of one of my good tenants and set up wireless cameras on the outside to capture the common areas and post signs.