Actually, the best rates are to be found on Caye Caulker! On AC you'll find everyone quotes the same prices, give or take, for one simple reason - most operators don't run boats out there but buy places from three operators who do. Depending when you're here you may find little choice - not all three will go every day, and in fact there will be days when none go. You benefit by being on (hopefully) less crowded boats, but lose by not being able to bargain much. Someone has to pay for the very costly fuel!