According to the International Franchise Association, almost 4% of all small businesses in the U.S. are franchises. It's an industry that generates more than $ 2.1 trillion and employs 18 million Americans.

One of the most appealing reasons to buy a franchise is that you're buying a proven concept rather than starting a business from scratch. The operating details, marketing plan and advertising campaigns all have been developed and tested by the franchisor, and often you can connect with numerous other franchisees to gauge what it takes to be successful.

All that convenience, however, can come with a hefty price tag. To open a Taco Bell or McDonald's franchise, for example, you have to have at least $750,000 in liquid assets. To open a KFC, your net worth has to be at least $1.5 million. The average initial franchise investment is $250,000, excluding real estate, says the IFA, and average royalty fees paid by franchisees range from 3% to 6% of monthly gross sales.

Fortunately, there are other franchise choices that cost a lot less to start and still offer you the chance to be your own boss. The Franchise Business Review, a leading market research firm that sort of acts as the "Consumer Reports" for the franchise industry, recently identified 10 low-cost franchises that let you get started for $15,000 or less in cash.

"Many people think you need hundreds of thousands of dollars to buy a franchise business, but the reality is that there are some great low-cost franchises that can provide a very high return on your investment in the long run," said Eric Stites, CEO and managing director of the Franchise Business Review. He added that some of the greatest opportunities are in franchises most people have never heard of before.

Among them is Image One, a janitorial cleaning service.

After a 20-year career as a sales manager for an electric tool company, Bob Caramusa opened his Image One franchise in Chicago in 2010 as a way to own his own business and to make some extra money.

"I have a wife and three kids, so the price was very important to me," he said. For $15,000 Caramusa says he bought "a complete turnkey business." The investment included equipment, training, ongoing support from the franchisor and two accounts to get started. "The financial risk was pretty minimal, so I knew I could make my money back even if I didn't stay with the business," he says.

Caramusa did stay, quitting his corporate job in 2015 to work on Image One full-time. Today the business is on track to book revenues of $1 million by the end of this year. Said Caramusa: "I wish I would have done this the day I graduated from college."

According to the Franchise Business Review's Franchising@WORK 2019 Employee Engagement & Compensation Report, 90% of corporate franchise employees rated their job as "rewarding & satisfying," with 56% responding "strongly agree" and another 34% responding "agree."

That's good news, especially with more Americans looking for alternative ways to make money, realizing they don't have enough in the bank for retirement.

"Franchising is about to experience a significant growth spurt over the next decade," said Stites. "Investing in a franchise business could be a great way for many people to supplement their retirement, especially with some really great, low-cost opportunities available that can provide income, flexibility and long-term equity."

So if you aspire to be your own boss but don't want to break the bank and build a business from scratch, these low-cost options may be for you.

(Figures reported are from each company's 2018 Financial Disclosure Document.)