What is the product or service?
I'm assuming it's for Dominicans as you are in BV mall. What's the age demographic?
If you are talking 40 or younger as your core customer in the DR and it's a physical product (fashion, furniture etc) and no online sales, look at Instagram. It blows away everything else in regards to CPA and it can get very viral, very quickly if you know how to target your demographic.
I have seen it drive some very nice numbers, specifically in Latin countries. If it's a service, then social media and website combined.
As I have said, a lot depends on who you are trying to target and with what.
If it's a younger demographic, look at social media and a website as a distance 2nd.
Certainly social media is critical in an all-encompassing marketing program. But while it's true that Instagram appeals to young 'uns, it has some structural weaknesses that inhibit the broadcast of "message." And certainly, properly used, can be quite effective short term.
But like Facebook vs. website, it's not "either/or." It's best and most effectively used as an important complementary tool to get word out quickly for sales, hot items, etc. Like FB, it's difficult to get a broader, more nuanced message out as to who you are, and why you're different. Why? Because it's been proven over and over that the mind buys what the eyes see. And the social media platforms do not allow for specific graphic customization and presentation of message. The limitations are endless as anyone who has tried to upload a 179x179 profile image can attest.
And now that FB bought Instagram, we can assume that FB-esque policies can begin guiding that platform---which can be very frustrating (ever try to get in touch with FB on an issue that is harming your page? Good luck.). And besides: you really don't control social media. They do. They own it, you don't. And prudent business people don't put a lot of assets in anything in which they have no real control, certainly not all their eggs. Not to mention in social media you're just one in a crowd of a bazillion with no real way to differentiate yourself.
On top of that the taste of young 'uns change on a whim. I just read that FB is growing only 3% a year, and that represents a huge decline. Yes, they are large, but the young 'uns are moving on to the next coolest thing. And they will do it again. Look at Twitter: once the Cool Kids fave, it's in a death spiral.
That said, IMO FB offers the most cost-effective advertising for targeting specific demographics anywhere, and you don't have to get all wadded up over "key words" and bidding for placement like on Google or other search engines.
I recently ran one small campaign on FB targeting males 21-65, living in the Dominican Republic, with an interest in motorcycles. For $48 my ad was served to 90,840, received 14,278 page engagements, 39 page "likes" (which feeds future campaigns that will add to my email database), 14,098 click-through and resulted in 375 "information requests" emails from the website, and 22 people who want to put a deposit on a $5000 product.
I have spent $250 in total on FB and have a database of 1400 email addresses of interested potential customers. This is a classic example of using FB to drive traffic to a comprehensive, popping graphic website at a very cost-effective investment.