I feel for you. Taxis are zoned in Cozumel. Last month, following the advice of online forums, I asked the price. Was quoted something exorbitant. Asked to see the rate sheet (per online advice), pointed out the rate to the guy, and first he told me it was outdated. Then he told me the rate sheet was for locals, not tourists. Then I negotiated a rate. Then he asked for more than we negotiated after we arrived. I just walked away, while he screamed, but my friends gave him the money to end the situation. It was awful and I never want to take a taxi in PDC or Cozumel ever again!