We did Gumbalimba on a ships tour last Feb. Very nice place, but I seem to recall its was only available thru ships tours. Also don,t recall any taxis at port, but there may have been. Suggest you Google Gumbalimba Park. They have a web site and E-mail and can probably answer all questions.
I too have heard they only book through the cruise lines when ships are in port. We'll be there in March 2008 and plan to book through Carnival.
Some people say they've gotten in and some say they've been turned away.....but if I'm all the way there I don't want to get turned away to save a few dollars....plus Honduras and Belize really are not the safest places to be traveling around by yourselves if you really don't know what you're doing.
I checked with Gumbalimba Park directly and was told you must book with the cruiseline. That being said, my husband and oldest son did the canopy tour and loved it. My younger two kids and I did the pirates, birds, and monkeys. The kids loved it. They got to hold a monkey and have a bird perch on their shoulder. It wasn't what I expected as we were herded in a group and stood in line to pose for a picture with the animals. I thought there would be more interaction. We did get some great photos, however.