Just got back from Bonaire. What a wonderful place! Airfare will cost you $$$. It's not the best place if you are looking for value. It runs about $550-600pp My husband and I did all shore diving for 10 days for a grand total of 28 dives! We where exhausted but it was well worth it. We stayed at the Divi Flamingo. Great place. They have a great dive shop...2 tank dives in the am and 1 tank in the afternoon.
Bonaire is more $$, but if you are going to go in Sept, you'd be sure to have good weather as it isn't in the hurricane belt.
The food in Bonarie is great! We'd eat a big b/fast at the hotel in the am, pack snacks for lunch while we were out for the day, and then we'd go out for a nice dinner. We saved $$ by hitting the grocery store and buying snacks and drinks rather thank going our for lunch everyday. We found some really fabulous restaurants for dinner.