I use a bucket fermenter (Ale Pail) and an Igloo Ice Cube cooler. It's not as nice as a carboy because you don't get to see what's going on, but buckets are stackable so they take up less space, and you can store other stuff inside them. I line my bucket with a garbage bage so the inside doesn't get scratched, then store all kinds of misc. homebrewing stuff in the bucket in the closet, so it takes up much less space (bottle caps, small bags of stuff, tubing, etc.). They're also easier to lift and clean. Carboys obviously also have advantages, but not so much when it comes to storage.
When it's warm out, I put the fermenter in the Igloo cube cooler with water and ice. This is known as a "swamp cooler". The cooler is about 17"x17"x17", so you could store your buckets in there when not in use, and it would work with carboys as well. If you put a large bottles of ice in there once or twice a day (1.5-2L) you can maintain the temp in the low 60s very easily. It is not as accurate as a fridge of course and the temp will fluctuate, but if you are around to monitor it, you can get it to stay within about 4-5 degrees, even if the room is 80-90°F. This kind of temp control has given me great results and clean fermentations. Some people recommend draping a wet t-shirt over the fermenter also, since the wicking will also help with the cooling. I used to do this but have found it unnecessary for 5 gal batches, since you can fill the cooler up past the 5 gal fill line. Another reason I stopped doing the t-shirt, is because it has grown mold on it, which you don't want near your beer or in your apt. I also use the cooler for keeping beers on ice at parties :)