first off- if you are booking an event through your resort activity rep make sure you know who they represent.
If it is Expedia, their prices are about the same as the general public if not slightly more.
If you are staying at a resort through your timeshare check their activity center. You maybe pleasantly surprised on their rates.
here is an example of prices for the Drum of the Pacific Luau
Expedia (retail price)- adult $110.00 child $65.00
Expedia promo price- adult $95.00 child $65.00
Hyatt price- adult $95.00 child $65.00
timeshare owner price- 2 adults & 2 children $204.00 (seriously that's it?)