Help with figuring out cap rate

[David Jenkins]

I'm a realtor / investor who has a few investment properties that cash flow well. In the past I've done nothing more than a napkin analysis to figure out cash flow, which has somehow worked. 

Now I'm finally getting around to learning how to determine cap rate. Taking a first crack at it with a 4-unit building for sale near my other investment properties. Here's what I have so far: 

Asking price: $1,174,000

GOI: $77,040 annually

They provided no expenses on the listing, so I am estimating them based on two other 4-units I own in the area.

- Water & Power: $1800 annually

- Gardner: $1440 annually

- Repairs: $5000 annually

= 68,800 NOI = Cap of .05%

Does this look even remotely close? 

I take it that I do not take into consideration some of my future expenses such as mortgage, taxes and insurance to also determine the cap -- Or do I? 

Thanks!!