Investing in real estate can be an excellent way to generate passive income. While buying a rental property could set you back more than $100,000 after factoring in the down payment, closing costs, and repairs, other real estate investments have a much, much lower initial investment. For example, it costs less than $60 to buy a share of Realty Income (NYSE: O) or W.P. Carey (NYSE: WPC), which both offer attractive passive income streams.