I picked up one of those $25 composters as mentioned in this thread:
http://forum.calgarypuck.com/showthread.php?t=59494
But you can actually pick these up from the Eco Store downtown at this price at any time I believe. I stuck in 3 bags of grass clippings, and yeah, on that first day it filled up to about half-way, but then after watering it down and leaving it for a few days, it shrunk a HUGE amount, like maybe down to 1/3, and still going. I wouldn't be too worried about not having space in a composter for it. And if it really was a problem, you could always buy 2
And as mentioned above, you can always just mulch it down.