Hello,
I've got a great suggestion that fits well within your budget!

Have a look:

Fly to Aruba and stay at the Mariott.

Antigua Marriott

Try a RIU resort. I've been to three in Mexico and Jamaica. The service is stellar. Maybe because it was my first, I love the RIU Tropical Bay in Negril the best. It was brand new when we went and I was well respected at the swim up bar!!! The grounds were immaculate and the people were so pleasant - they even got a kick out of us going thru our room's stocked bar in 2 days! And the food was delicious. There was jerk chicken shack right on the beach so you could laze about without having to change from your swimsuit or trek to the main dining hall. It was four and a half days of bliss and it was less than $600 with flight and everything. Oh yeah, the drinks; once I informed my new found friends (bartenders) that I liked to actually taste my liquor, they made each drink to perfection!

October is very cheap in the Caribbean because it is the peak of hurricane season. So, be sure, wherever you go, buy trip insurance that covers this possibility.
There are some lovely all inclusive outside of Cancun, about 1 1/2 hours down the coast..Also, some in St Thomas..You didn t say where you were departing from..But an all inclusive isn t always the best or cheapest. Stay away from Jamaica and Aruba. What about a Club Med? Don t know if they will fit in your budget..But they are super,,especially the one on Paradise Island, Bahamas..
You can rent a villa on the beach at Nail Bay, Virgin Gorda..not all inclusive, but you have your own whole house..Its the best place I have ever been..Sunset Watch upper is a 1 bedroom with private pool, maid service, fully equipped kitchen and comes with a jeep for the week..DVD/CD, Internet connection, air conditioned, King bed, and queen sleeper in living room, huge veranda

if you really want a beautiful place to spend your vacations for the ½ price than in others destinations go to Dominican Republic…..plenty of sunny,white sands and warm water beaches,the music merengue and bachata are famous all around de world…………….. the food is richs in flavors and variety,a lot of sea's fruit….good rum and tabaco.but if you prefer mountains there you get "constanza" a little and beautiful town with down temptures(less than 0 celcius)the whole year(www.constanza.net)where you could see all kind of flowers,and exotics fruits and the highest mountain of the antillas "el pico duarte"(www.picoduarte.com.do).
In Santo Domingo(the capital)you will know the first university,the first cathedral,de first hospital and first street that were constructed in america because was the first place where columbus put his foots.there are excellents all inclusive hotel(was in Dominican Republic where the "all inclusive" was born)like barcelo's,ibero star,riu,club med,occidental,casa de campo…….. with casinos,golf fields,unlimited national & international drinks and all the services you can think, if you really want more information you can enter in a web like or or if this is not enought for you and you know speak spanish or portuguese write to me to:sartorini_sartorini@hotmail.com because my english isn't good enought.
aaaahh!!!!!!!! i forgot to say:despite is a little island,Dominican Republic have 8 airports so if you want move from a place to other quikly you have the airplane option..the highways are pretty good anyway and each place is near from the other.