i use a $25 small white two door office cabinet. It's made of pressboard and painted dull white. dimension are approximately 30" high, 24 inches wide by 12 inches deep. I fitted it out with weather stripping, caulking and other techniques to deal with light leakage, installed a small fan on the bottom as an intake (and cut a few passive holes) and one at the top as an exhaust. works great...got it at either Lowes or walmart ( <-- i realise those are only good to US peeps, no idea what would be the equivalent overseas). It's one of those you assemble yourself and found it I believe in the closet or room organisation area. here's a pic:
