Humidity Controlled Air Coolers

I am residing in a coastal area where the normal temperatures in summer will be 42 deg. Centigrade, with a humidity of 80%, i cannot afford for an air conditioner, can anyone suggest me what is the cheapest system i can go for, so as to maintain the room temperature at 26 - 28 degrees centigrade (in summer) by controlling the humidity. I was planning to buy an de-humidifier which controls the humidity. Does it work, or are there any other alternative ones.