You have many options.
Option 1: Buy a larger "used" apartment sized fridge. One of those fridges just big enough for one fermenter, put a Johnson Temp Controller on it and you have a way to control temp. You can usually find them on Craigslist for $20 to $50. If you want to expand it, remove the door and build a box that will hold two more fermenters that is open on an end (attaches to the fridge at this opening) and open on the side (the opening needs to fit your soon to be repositioned door). Liquid nail the open end to the fridge where the door used to be. Put the door on the other opening. Insulate it, hook up your temp controller and you now have a fermentation chamber than can hold three fermenters.
Option 2: For cooling only. Put your fermenter into a shallow container of water (4" deep water level). Wrap a damp towel around your fermenter and put a fan blowing on it. This will drop your fermenter down about 4F to 6F from ambient room temperature.
Option 3: If your room is always cooler than you want to ferment at, you can wrap a heating pad around it and plug it into a Johnson temperature controller. Put the "sanitized" temperature probe into your wort. If the wort gets too cold, it will turn the heating pad on and warm up your beer. When it gets too temperature, it will turn the heating pad off. If you don't want to spend the money on the temperature controller, you can monitor the temperature yourself and manually turn it on or off, as needed.