Whether you are hiring a DJ, a photographer, florist, event planner, or videographer for your wedding or event- a true professional will save you headaches and heartache in the end. I don't know how many events I've attended where the client saved several hundred dollars by hiring a family friend or 'budget' company to DJ- for example- only to have his gear fail, or play the wrong song during the first dance, or offend the guests.
Hiring a creative professional videographer or photographer is also critical, since those precious moving and still images will hold the memory of your day for you and for your loved ones for generations to come. A wedding couple recently hired me to film her wedding a few weeks before her event after the cinematographer she booked for substantially less stopped returning her emails and phone calls. Unfortunately, the bride may lose her entire deposit from that unscrupulous company. (Thanks to Brett Culp for this image link)