We flew WestJet to Jamaica this year from Ottawa (great price) and they have "buy on board" meals. E.G. a selection of sandwiches, chips, pop etc. After checking-in at the counter we headed for the "Island Grill" located at the entrance of the Montego Bay airport terminal (facing the WestJet counters) and purchased meals to bring onboard our flight home. We got 2 Jerk chicken dinners (Jerk chicken, rice and peas, salad and a fried dumpling) for US5.00 each! The meals were great and except we had to put up with quite a few envious glances from others on our flight. Even the WestJet flight attendants were asking how to get this at the airport. Just thought we'd mention this option for other folks flying home. Island Grill is a very sucessful Jamaican food chain. Check them out on Facebook!
P.S. you are allowed to take meals through the security checks, just no drinks!