The answer is booth rental. Milady states directly: booth renting is possibly the least expensive way of owning your own business, though it comes with complex regulatory requirements.
The book notes that a large share of working barbers and cosmetologists are booth renters, and flags that the following chapters cover booth rental in more detail specifically because of its legal complexity. An independent local chain, spa, or regional franchise all require significantly more capital to open than renting a single booth.
Milady Standard Barbering, 6th ed., Ch. 19 (Preparing for Licensure and Employment), p. 716: "Booth renting is possibly the least expensive way of owning your own business, but this type of business is regulated by complex laws."
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