Check out this website for info on flights via Jamaica Air Shuttle - just a bit higher than Air Jamaica, but not much depending on the day you fly.
Baggage allowance same as many international flights - one free bag not over 50 lbs and one carry on.

http://www.jamaicaairshuttle.com/the-community.html

Air Jamaica used to be the same as any international flight through MoBay. The plane was usually about half business people and half tourists or Jamaicans flying with luggage.

I used to like flying in and out of Tinson Pen - the smaller airport. Very little walking and you can get there half an hour ahead. Quick boarding, deplaning and luggage retrieval. Saves some time overall. And the flight is well worth the money for the scenery alone. Gorgeous to fly in low and slow when the weather is good. Everyone should try taking a small plane in Jamaica at least once -- for the experience.