When do you want to go there?
Actually German travel agencies are offering specials for the Gran Bahia Principe El Portillo, for example 7 days at the end of July for 245 Euros per person, will be around 50$ per night and person. At the end of November you?d have to pay around 55$. All inclusive!!! Could still be cheaper when booked by US/Canadian agencies.
The GBP El Portillo is the best but most expensive hotel around Las Terrenas, a really nice place, good food and very special cocktails ;=)))) I was there 2 times and really enjoyed it.
If you don?t want to spend so much - there also are cheaper but easier hotels at Las Terrenas. At Las Galeras you find an a.i.- resort called Grand Paradise Samana, I was there in March, which actually is "sold out" for around 30$ one day, but food is said to be very bad actually. But at LG there?re lots of private bungalows, appartements...
Saludos