Export Costs
Several companies ship to Port Everglades and Port of Miami in FL, as well as Jacksonville, FL, and probably NY. You must use a DR freight brokerage to ship, but you will also use them to find the costs to do so.
A 20' container will cost between $3000 and $4000 to ship to Miami, cleared and ready to load onto a truck to the interior of the US, and it is probably safe to assume $1.50 - $1.75 a mile after that.
For a 40' container, figure the shipping cost to Miami from Sto Dgo would be $4000 to $5000. Because the trucking costs after clearance is the same cost for either a 20' or a 40' container, if you can fill a 40' , go for it, and reduce your per-unit cost of shipping. Otherwise, have the freight unloaded in Miami and reloaded on a separate tractor trailer .
The costs above include delivery to the port in the DR, DR freight broker costs, Ocean freight, US Customs clearance and port charges, and the costs for the US freight brokers. Trucking cost is separate within the US.
You need to also check with a US freight broker as far as other issues such as US Customs for termite inspections, etc concerning wood items shipped into the US, and what you need to do regarding this.
Also- you need to really check out all of the documentation that is required by the Dominican department that is supposed to "Promote" exports, as their requirements are quite extensive, and it is possible their function is to promote paperwork.
Also- the DR is a signatory with the US on the Caribbean Basin Iniative, which allows almost all products manufactured in the DR to enter the US as duty-free. There is a similar treaty with Canada. The US freight broker you talk to will be able to answer all of your questions about this, or you can find it on the Internet under "C.B.I."
Good luck.