I always rent from a place across the street from Bailys Restaurant in Sosua. It's called Wilbert-Bank Car Rental on Calle Duarte Alejo Martinez # 20. There's a guy there named Fransisco that I always deal with. They take a copy of the passport if you don't have a credit card. I have rented with them the last three times I was in the DR since August 2011 and have never had a problem. They charge around $1300RD per day. When I pick the car up I film it with a camcorder, walking around the entire vehicle and making sure they see me do it. Maybe it's that that keeps them on the up and up, I don't know, but I've never had a problem with them so far and I plan to rent from them again next week when I'm in Sosua.