I may have an answer to my own question. One of the excursions offered is a trip to DePalm Island, an All-Inclusive place where you can apparently get a massage on the beach for a reasonable price.
Not that I'm cheap (okay, YES I AM!), but I remember beach massages in Costa Maya being offered for $20 for an hour; actual spas in Aruba (a couple offer beach massage) were upwards of $100 pp. DePalm mentions beach massages (15 to 30 minutes) in the $30 to $50 pp range.
Only catch, I suppose, is having to book the excursion to get there.