It says"Over a portfolio, over time, your operating expenses (not including financing  costs) are going to be approximately 50% of your income"Notice that is Does Not say "every property will have exactly a 50% expense ratio." 

Are they insured, operating under a brokerage, Licensed, etc...We run into all kinds of companies that are illegal start ups and use uninsured cash laborers.

CAP rate is a function of market demand and actual Net Operating Income.See if the seller will provide you with three years of Income and Expense statements. 

I own a partial interest in an LLC that owns/operates a mobile home park.

Are you actually prepared to operate a business.

Owning and operating real estate will not qualify.

I handle most maintenance and we always have a renovation running.My grandparents ran much the same sort of operation in New York City many years ago.

Annual income is 70,320 with net operating at 53,171.

@Vlad Denisov if this is a live deal you have to follow the waterfall sequence as written in your operating agreement.

If all cash, disregard everything I said, except, check with applicable state law as to any laws you have to comply with relating to the sale of any properties.