Interesting old thread. I was wondering about heat issues in my room as well. I'm on a tight budget (around $200). Humidity in the summer around here is between 10% and 30% and the temperature is between 85 and 105 most days. It's cooler in the mornings (around 60-70) but with slightly higher humidity(35-50%)

I'm thinking that a swamp cooler would work best since it doesn't use very much power, and I don't have and windows to mount an AC unit. I have a good filtration system which I believe should limit the effects of the swamp cooler raising humidity. I've also got a dehumidifier just in case.

Anyone have any experiences with swamp coolers inside grow rooms in a dry climate?