Watt:
When we go, we stay in a condo with kitchen also and we bring staple foods. For example when we get up and are too hung over to bike to town I bring cereal packs (buy milk there) or cereal bars. Other things we take:
Pasta/rice - to make when we cook up our fresh catch
Mac & Cheese - to make when our lazy butts don't want to walk to town to get lunch or mid afternoon snack.
granola bars - to eat before we go diving
candy bars to freeze and eat when we get back from diving.
Then buy the rest - veggies, butter, salsa, fruit, fresh goods from kids on bikes in the AM. But I like to take our staple foods for when we get a little lazy or too pooped to go to town. We do eat in town almost every night though (and re-stock misc. items while we are there, ie slasa chips, limes). The stuff we take is just for munching
have fun
AmbergrisCaye.com 
