I have brought several large groups to Negril over the years so I understand your frustration. I usually purchase 3 to 6 months out if possible. With a group I wouldn't wait for a last minute deal. When I am in search mode I use Kayak, Vayama, Orbitz and the airline sites and I check frequently. I have heard good things about ITA Matrix but haven't purchased through them. The airlines usually release sales in the wee hours of Tuesday or Wednesday nights, but the best fare I found last time was a random search on a Saturday and the next day the price had more than doubled. I also set up fare alerts on the sites that allow it so I get email notification of a price drop. It really shouldn't be this difficult but perseverance is they key. Pick a price range you are comfortable with and when you find a price that fits it, buy and don't look back. Otherwise you will drive yourself crazy.
Good hunting...
