Not sure of every detail, but the most affordable rooms at Negril Yoga Center are 20 dollars, and there's a 15 percent off coupon on negril.com -- that's 17 bucks a night! Might have to share a bathroom but a good deal at less than 100 per week.
I hear this place has a lot of BIG crabs crawling around, which is something a little different. Something about the location.