TUFF N UFF has an all week pass as well as a 5 day pass. The all week is 35 dollars, and the 5 day is 25 dollars. They run between town and Belizean Coves, Belizean Shores, and CoCo Beach. I am sure if you are up the island and within walking distance of either of those resorts, that is your best bet....
My family and I (party of 4) usually do this, then we don't feel the push to only go into town once and get everything done, and consequently be exhausted.
You can buy the pass at the TUFF N UFF dock in town....
Have a great trip!!!!!