Imagine two weeks before your wedding, the performer that you were guaranteed is suddenly substituted because they received a better monetary offer from another company or client. Now you have a Disc Jockey you have never met performing at your wedding. You will no doubt be completely stressed, wondering if they will represent you well, let alone show up. Prices are also an accurate indicator of how a service operates. If the price is too good to be true, be wary.
Low prices can be a direct sign of a company that is ignorant or noncompliant to the tax system.
Second, obtain proof of legitimacy. Ask if the company carries liability and workers' compensation insurance. There are serious penalties for employers that do not carry workers' compensation insurance. In fact, if you contact a company that claims they do not need workers' compensation insurance, they are deceiving you. The truth is, if they establish a contractual relationship with you indicating an obligation to perform and send someone that works for them, the performer is an employee by definition.