Are you a long term planner?
How about next fall in Mexico? $308 RT
There are dates in October and November available mainly flying on Mon, Tues and Wed. This is on USAir which is well, one of my least favorite airlines but who cares! Connecting through PHX which is not so bad.
ALso Hotwire has some great deals for all-inclusive for up to 4 people in the same room for about $100 a day.