You have a great question. Just like an investment type property, education and hard work will go a long way. There are 6 and 7cap rates out there for almost any asset class.
Steve and I buy mobile home parks on 10-12+ cap rates ON ACTUALS! There are additional profits realized on reducing expenses and raising income (increasing rents and filling empty lots). There is also a huge profit center by buying mobile homes as wholesale prices and selling them at retail (whether for cash or owner financing).
I would stongly suggest getting Huge Profits in Mobile Homes and Mobile Home Parks as a great intro course.