I asked the local manager of my guesthouse about renting a house. He said that you could get a house near the beach for RM1200-1500, but an apartment would be preferable and more expensive because of security. In Batu Ferringhi houses are robbed regularly. It is not possible to rent a furnished house because owners don't want their things stolen. He said that if you want a house you will need 24-hour guards, which will run about RM800 per month per guard, so for three guards, you would spend RM2400. Most people get into houses because they are cheaper, then move on to apartments when they can afford them. Locals, not just expats.

All the higher prices I heard were for furnished places. The lower ones, like MR700 were most likely for unfurnished places, and just for the off season.

I hope this helps.