I've just confirmed my contract for Now 8.22.2015.
I am bummed that all that was available for the ceremony slot was 3:00pm. It seems too early for beach ceremony...
But, I am happy that I made my selection, have my site up and running for the guests to book, and now I can finally focus on the theme, and saving money!
So I travel to the DR throughout the year and November Thanksgiving week is expensive but after labor day through 2/3rd week of November is the winding down season... then it picks up for december holidays. Please note that because it is considered the low season, many resorts do their renovations, additions, construction and remodeling around this time. It is cyclical so, they do not do renovations every year, but just be mindful of this possibility.
Fall in the DR is beautiful. You should be able to get prices under $1500 if you do that hard leg work like Jamie said. Good luck.