We looked into this in March for Antigua- the passes were in the $75-100 pp range. This was a considerable increase to what we had thought originally of $35 pp. We chose not to go, took a nice taxi tour then to the beach for the day.
I would suggest going to the Sandals website and send an e-mail to verify the cost, it may have changed. We thought the price was a bit much for a day pass. I have been reading about another option in Antigua for our next trip - Allegra Pineapple resort. We may try that in December.
Good luck and enjoy!