Here, I will disagree with the majority about bringing down the stuff in person. I do have experience bringing in laptops, cameras and cellphones via the shippers.
Two years ago I bought a US$1000 laptop from US manufacturer. I paid about RD$5.000 in taxes and about RD$2500 in shipping. That was through EPS.
A year ago I got Nokia cellphone costing US$270 and paid about RD$1000 in taxes (duties). Shipped via Piksend.
If your package has invoice you should be OK. Over the $500 item I would ship through a well known shipper like EPS or Vimenpaq so you're assured the customs will be OK.
8517.12.00 - - Tel?fonos m?viles (celulares) y los de otras redes inal?mbricas 3.00% 0.00% S
So cellulars pay 3% customs duty and 16% ITBIS VAT. Total 19% of the value over US$200, including the USA inland shipping charges (so get free or cheap shipping if possible).
If I am not mistaken, laptops only pay 16% ITBIS, no customs duty or excise tax. You can call Vimenpaq (asks for "deparamento de aduanas") to double check.
A nice thing with Vimenpaq is that if DR aduana charges you a customs duty/tax based on incorrect value amount, you can file a claim with Vimenca, supply your credit card receipt, auction receipt, Paypal receipt, invoice, link to a website, etc. and they will get back to aduana to reprice the article. The article will be on hold in your local Vimenpaq (takes about a week to process) and then your invoice will be adjusted. Or you can pay the total and any adjustment is then applied to your Vimenpaq account against future shipping charges.