Jamaica is the best island in the carribean any time of year period.

I guess it depends on what you're looking for - snorkeling, sailing, entertainment or just a quiet time. Punta Cana in the Dominican Republic is a great place to visit all-year round - it almost never rains there, and it's summer time all year long.
Check out this article on Caribbean Islands based on activities and lifestyle:

Depends on where you look, then it won't look so expensive.

But I highly recommend Barbados!

Pegwell Inn Guest House: and/or 246-428-6150. The cheapest accommodation out there as compared! This location is close to the beaches, amenities, fast food restaurants, the fish market in Oistins, post office, even the pharmacy, etc.! Across the street is a plaza called Southern, has supermarket, barber shop where there's also hairdressing, GOOD DEALS! And it's even close to public transportation, either a minibus, route taxi, or a bus for $1.50 BDS each way. You can take the big bus to Bridgetown or even stay on the Speightstown bus to go to Speightstown!

And keep comparing the flights, and once you get a price you can afford, grab it while you can!
Hope this helps.

Not expensive and a lot to do :
Puerto Plata ( The bride of the Atlantic" Dominican Republic,
new beaches (restored) lot to do and to see, all inclusive resorts at all prices!
I´m a tour operator here, so if you need more info, just contact me!
Enjoy your time with us!

Go to Aruba. The weather is the same all year round 85-95, give or take, plus April is a great time to go since the rainy season is usually Oct. and Nov. meaning not a lot of rain just a sprinkle here or there. The prices in Aruba also stay the same all year round. Depending where you are from, i.e NY the food and drinks are the same there as in NY. So no problem. If you are into any type of water activities this is also the place. So go there.