For GOSH sakes Phil, SLOW down!!!! Everything takes time in this country. Where are you staying before you go down to Las Terrenas, surely you're not going down there the day that you arrive? If so, why buy a car up here, wouldn't it be better to buy your car down there??!!
Nearest car dealer to Puerto Plata airport is Sosua. Nearest HONEST car dealer is perhaps in Miami!! The nearest "best deals" would be able to be seen in Santiago where there is much more choice (& competition!!). YES, I can recommend my mechanic to come with you, he would need about RD $2,000 for a full days work - but he DOES speak English & he IS honest & reliable .... I trained him myself!!!!
I know of a 1996 Chevrolet pick-up 4 cyls, with A/c, recon engine etc going for RD $150,000 (negotiable), which includes 6 months worth of Fully Comp insurance. Haven't checked it over yet, I only got the information today. It belongs to a woman friend who is going back to England for a short while. If you want more info I will gladly go check it out with my mechanic friend.
Bringing in your laptops should not be a problem - you are only here for a "holiday" after all!!! Well, that's what you tell the customs people, you'll be taking them back out of the country when you leave in two weeks time!!!
If you need more, e-mail me. I live in Puerto Plata & can introduce you to some rogues who mascarade as car dealers!!! - Grahame.