:trismug::tritongue::triwink::tribiggrin:The key as to what to charge is inherent in your own mind (WYW) and abilities, equipment.
Most of us, but I speak for myself, deliver a product based upon variables; time, size of sound system, load-in issues, mileage. If your claim is "mobile dj" then travel is an issue. Last year I travelled 4.5 hours (one way), stayed overnight in hotel day before and night of wedding. I suppose you'd consider that for $550 and not blink an eye? Some of us include lighting for dance floor and room decor lighting in our price, others choose to bill as additional to the flat fee. So, there is no standard price other than what we figure in our head, so-to-speak.
I have a flatt 4-hour price and a 5-hour price. If someone want 3-hr, its the 4-hr price.
Like others have asked, where you from? What's your price? Please entertain us with your particulars.