I didnt find anything like this in Puerto Plata at all, dont know that place recommended by windeguy but that would be cool if they have equipment like that. In case that place does not work out, there is a place in Santo Domingo that will ship equipment via Metro and you can check out the items online. The place is called www.Musitempo.com
I had no problem with customs, just order each item as a new order. I mean every item was under 200$. Was shipped to Miami free. I paid around 6000pesos just for the weight when i received it in the business mail office.