Booking excursions while in port

I was just wondering if anyone ever waits until there in port to book independent tours/excursions?

I vaguely remember doing this in Nassau & Ocho Rios years ago. I remember just talking to the taxi drivers or other passengers and going right then. Not sure if those rate were cheaper than if I would have done some research, but it work out then.

If anyone has sailed to Falmouth, Grand Cayman, or Cozumel and waited to book once you go there , please let me know about your experience?

We went to Cozumel and just took a taxi to Chankanab park. There was a line for taxis which you just joined and told them your destination and they put you in a cab. If a few people were going to the same place they had them share. It was very easy and quick. It cost around $10 (can't remember exactly) and then we paid the normal entrance to the park. I'm sure it was a lot cheaper than the ship excursion. I cant remember how we got the taxi back but I don't remember it being difficult (i think we asked the taxi driver and he told us what to do).