I'm doing the same thing, so peep the scene!
Ok, so I've done the research, have a wedding party (reception) set up and the whole nine yards, so some of this info might help.
I reserved a nice place (a banquet hall) called "LA ANTILLANA". It is a large hall that will hold between 250-350 people comfortably with a dance area (you know we Dominicans like to party!). Now, my party is only 110-120 people, but I wanted to be sure we'd have plenty of room for dancing, so I got the big room (they also have a smaller room). The hall itself is RD$11,000 with taxes, and the smaller one (I think) was RD$7000. I am having them cater the function cuz I didn't want the headache of coordinating an outside caterer (RD$23,000 for 110 people). Also, they will give me a DJ for RD$3000. All in all, I'm getting the place with food, music, 3 waiters, bathroom attendant, etc, for RD$42,278 = US$1262.00 as of 11/13/06. I am taking care of drinks separately just because I have connections for that, but you could get that through them too. Decorations also are separate, although they provide tablecloths and silverware, glasses with the buffet. I priced lots of places, including Amaprosan where my aunt is a member and in my opinion, its a ripoff compared to where I got mine set up. FYI, you don't have to spend the equivalent of what you'd spend in the US in the DR. What I mean is that if you want to spend $5K, by all means go ahead, but I planned on spending that much myself, and so far I'm @ about US$2800 with decorations, mementos, and table arrangements, including freight from home in Massachusetts... I plan on spending the rest on my honeymoon!
La Antillana: 809.583.4828
809.5838030
ask for Helen Grullon, she does reservations and planning.
Pm me if you have any more questions, but I leave on Wed the 15th, so wish me luck and expect a trip update when I return on the 30th