I hate small planes but some people tske the Tim air or International airlink I think they are called. Pretty expensive and sometimes they don't save much time. The couples shuttle is included in your vaca so we sit back and enjoy the ride.
We've been to CSA 6 times. Returning in March for #7. Last year we flew TimAir from MoBay to Negril. About a 12 minute flight down the coast. My wife was a little nervous at first but now she is hooked. We arrived in MoBay at 9am and was on the resort by 10:00. It was awesome. $210.00 US was the cost. It allowed us to start our vacation as early as possible. We are sad to leave so the shuttle on the way back to the airport was fine with us. The pilot was great and flew right alone the coast line. Great for a diffferent look at the island and some great photos! Booked again for this year! Which ever way you go enjoy Jamaica!!
For a private ride from MB to Negril you are looking at about $50/ couple. That generally includes ice cold Red Stripes (in the bottle) for the ride. Plus you can decide for yourself if you want to stop along the way (rather than some stranger on the shuttle deciding for everyone else). For us, the private transport is well worth it.