American Airlines has fare specials. The downside is that they are on short notice. The departure and destination airports vary, but you can sign up for an e-mail from them with their special fares. Sometimes as low as $99 roundtrip, and airports can be Ft Lauderdale, Orlando, etc and going to any of the airports in the DR.
Right now, they have a fare of $168 leaving Fort Lauderdale to Santo Domingo with departure as early as 06 May, with latest return of 29 May.