First off, there are courier companies that will haul stuff in from the states are fairly reasonable rates. You set up an account with them, and when your item comes in they will usually email you and you pay the transportation, handling and customs fees. The items have to be less than $200 or you get hit with big customs duties.
Then there are boxes and barrels. If you currently live in an area where there are some Dominicans, there is probably a company nearby that will deliver boxes and barrels to your house in the DR. Boxes and barrels are both of a standard size and there is no weight limit and the cost is a set fee of 70, 80 or 90 dollars depending on where you are.
I do not know if you have been to places like Charo's Decoracions here in Santiago, or Ochoa Hogar, or Bellon...They have a lot of stuff for your house (but you have not said what it is that you are looking for).
Finally, there is "corotos" a website that sells everything.. you can check there...
Stay cool, you can find some surprising things at reasonable prices.
Cordially,
HB