My question to those is "If you have a Limo service and you are charging a certain price, would you keep that price the same if you started offering Stretch Limos?"
not the same at all.
limousines are ONE complete object......so of course you'd charge more for the bigger one.
DJ + light show are two separate objects. They can be separated and given a value of their own.
sometimes FREE light shows are like FREE DELIVERY.
you're actually paying more for the food, and which pays for the "FREE" delivery.