When booking any sort of act for your event,
you should consider that the entertainers are professionals
and depend on their income from the event quite heavily.
The cost of entertainment varies substantially but depends
on many factors such as location, time of day, day of week,
personal contacts, size of the event, amount of equipment
they have to bring, a certain "hassle factor",
and any extras you require.
In general, figure about $50-$100 per person
per hour plus some fixed cost. For example, a DJ for
three hours will probably run you $200-$300 for a party.
Weddings typically cost a little more because the DJ will
be dressed up and will have worked with you quite a bit
beforehand in music selection, MC requirements, etc.
A band also runs about the same but keep in
mind the cost of bringing equipment. A quality five
piece band for 2 sets (i.e. they are there about 3-4 hours
with setup) will run $1000-$1500. A larger band, say
8-15 musicians will run about $1500-$3500 for a typical
show, more if it is a large event. The band leader
will typically hire musicians for the show depending on
the budget, so in many ways you "get what you pay for."
Dance Performances are about $25-$50 per dancer
per routine plus expenses. So a couple would get about
$150 for one number, and a large group might do 2 numbers
for $200-$500, though this is depends even more on circumstances.
Many dancers are also instructors so if doing a show has
promotional value to them, then price is fairly negotiable.
Tipping: generosity is never overlooked.
If you managed to negotiate a low price with the entertainers,
they spent a great deal of time with you on the phone, they
put on a great act, and you have the money, definitely tip
them. If you are paying top dollar in advance, it
isn't expected or necessary.