The middle of April is the start of the so called slow season. I have stayed at the Firefly Beach Cottages 7 times now. It is right in the middle of the 7 mile beach and has cabins that are very reasonable all the way up to a penthouse overlooking the Caribbean that is somewhat pricey, and everything in between. It is one of many reasonable choices on the beach, and everybody seems to have their favorites.
Check out the listings on www.negril.com and you can see where the locations of the different properties are - enjoy!