Marco at Rocky's is very often booked, but he will usually help you find another place for a resonable price. He once drove me around to help me find a room and he got me a deal by haggling in Spanish.
I also really like Tropixx, which is small and very garden like, but it has no bar or many other facilities. It has a honor bar where you can just pull beers out of a fridge which is a nice service. It is up the hill from The Playero but I think they are running about $50US a night so you may need to haggle. Another cheap place might be Eddy's Sports Bar at 571 1667. They had a few rooms in the back they were renting last time I was there but it is kind of out of the main part of town.