I do not doubt the "dj" was probably not paid, and probably a "relative".
But what about the guests?
Do they "know" it's just "uncle joe"?
The thing I don't understand about these "type" of events, is do the b/g ever honestly think about the guests?
Many may travel extensivly from out of town, or state.
Many may be "paying" for a sitter to "get out"
Many may not be able to get out on a regular basis, and "hoping" to have a truly fun and enjoyable night.
This is "one" point I like to bring up if the b/g are a little "on edge" about spending a few more bucks for better quality.