My husband and I had great massages at Paradise Beach in Cozumel. It was a $9 taxi ride from the port, no admission..they just expect you to spend some cash eating, drinking, getting massaged....
It wasn't busy when we were there, so the ladies went WAAY past the 30 minute mark. My only complaint was the oil got into my hair (from the back of my neck)and I looked a little greasy for the rest of the day. Would have taken shampoo for a shower if I'd known.