Click the link below to look at budget accommodations:http://AmbergrisCaye.com/pages/lodge/lodgingprice.html
As soon as you make your reservations (yes, definitely make them NOW), start researching good, well respected dive operators~ near~ your hotel and book your dives ahead. Be sure to ask about their cancellation policy if weather or other problems arise, such as ear problems, etc. I said near your hotel because it makes it easier to haul your gear back and forth, catch early trips, and because most surface intervals happens back at the dock so it's nice to walk back to your hotel to rest a bit, rehydrate, eat, grab any additional gear, etc.
By the way, your attitude toward all of us on the forum helping you is off putting. We are not paid travel agents, rather people helping people have a wonderful vacation and sharing our opinions and ideas. Having a positive and friendly attitude will take you far on this forum as well as on island.