Help me calculate profitability of this Multi Unit family deal?

[Ben Patel]

This is one of the deals I am looking at it's an 18 unit family unit apartment complex in an excellent area where the rent's similar will go for higher.

Here is the deal:

Asking price: 2.8 

Cap Rate: 6%

Avg monthly rant of all 18 rental is: $1200 * 18 = 21600 a month

Yearly revenue of $259,200

Vacancy: 5% (12,960 ) - I know this is low

NOI: 246,240

Exp: $74,000 a year (30% of the NOI) I know this is low as well.

I'm thinking the price is high:

Would it be reasonable to say the cost of Vacancy is 10% annually and the Expense of 50% of the revenue?

I know the seller isn't going to take a million less than asking price but am I wrong with my calculation?

Thanks