Yeah, from the reading on big beers I've been doing (I'm planning a RIS shortly as well), fermentation can be pretty intense, so temp control is pretty important.
You can try out a swamp cooler like flars posted, a lot of people use them. I just use a big rope bucket (this is the exact one I have... if you want one, shop around, I've seen them online on more specialty shops for as much as $30) with water that goes up to about the mid-point on my carboy, more or less, and I rotate frozen water bottles into it (2L water bottles, change them every 12 hours or so).
My room temperature is currently 77F and just by putting my carboy into the water, it kept fermentation at 72 when I was making a Saison, and I've kept a beer at 60-62 in the past, though I was rotating my bottles a bit more often for that one.
In other words, temperature control doesn't have to be fancy, just know that it won't necessarily be elegant either, hah. And obviously doing something like a swamp cooler won't be as precise as a temp. controlled fridge, but it's definitely better than nothing.