Or am I missing something in the math?  

I have been doing my homework and I know NYC is probably the toughest market in the US, but still hopeful that I will find some deals.I have RE investing experience but outside of the US which is very different, but still mortar and bricks. 

So the math works like this 5x 250, 4x100, and 3x50 or $1800/year real costs vs $2400/year of what they are willing to pay.

You are doing the right thing by doing your homework.  

Unless you've done all your homework, especially a comprehensive title search indicating no other liens, etc.  

Because I grew up poor living in a variety of apartment buildings and I have always done the basic math of what one could earn if they owned said buildings. 

I usually look for multi families near colleges because students are always looking for housing and parents are always paying, Make sure you do your homework and good luck!

As a beginner wholesaling would be a good start,just find a good deal get it under contract and assign it to a cash buyer and get instant cash flow,in the mean time you need to find private or hard money lenders and start build a relationship with them,they have high rates but doesn't require a credit check like a conventional loan. they go by loan to value on your deal so you need to do your home work and present them a good deal that will impress them,then they require you to put down 20% normally.

(accounting features, online payments/applications, owner payments, screening etc)And you have no idea how much I referred to the ebook - Accounting Debits/Credits always screwed with me in college - maybe a right brain/left brain type of thing I was always good at math, but for some reason those two always tripped me up as it really doesnt apply to the daily life version of how we use debit/credit or think of the concept when paying for things on our debit/credit cards etc -- Always had in my head debit was taking money away, however not always the case in accounting.  

I am a high school math and science tutor part time, but I an engineer by education.