I started commuting this year (65km round trip) and thought about getting some winter shoes. Instead I just used my regular road shoes and neoprene booties. The coldest I've ridden in is about -8 and they were fine for a little over an hour. Most of my rides are above freezing but the roads are often wet so the neoprene keeps my shoes clean (albeit not dry). I use wool socks.

Now that I've been commuting for a few months I wouldn't bother with heavier shoes. The booties work well and are relatively inexpensive. I'd rather have extra pairs of road shoes that can be used anytime than specific shoes that only work when it's cold.