I start S05 around 55F if I am going for a really clean ale. I've had very good luck with 1728 down at lower temps as well, I make a decent size starter and rouse the yeast a few times, (1728 is very floccuant might not attenuate as far otherwise).
Personally I keep my fermentation room at 50F in the winter and it's great. I have a water bath (large storage bin big enough for two carboys, $8) with an aquarium heater with a built in thermostat (on sale at a pet store for $30). The plastic housing broke off the thermostat which allows me to turn it below the 70-95F range, though it takes a little trial an error. I'm holding 63F right now because that is as low as I can take WLP002, I'm guessing a Belgian yeast is going to have similar issues this cold but I haven't tried.
You could also make a fermwrap for $15 with a dimmer switch in the circuit. I can't recommend a Brew Belt since both I've purchased failed on me pretty quickly.
Both these options are only like $.10/beer if you make a couple batches which is cheap if you consider what you are saving in heating bills vs the $50+labor you are risking in making a bad batch.