Last year I got some North Face Storm Peak II boots. This year they are called Storm Summit boots.
http://www.thenorthface.com/catalog/...mmit-boot.html
They're basically like a mid-height (basketball shoe) dayhiking boot with great insulation.
They aren't a cycling shoe, but work great with platforms. Rated to -25, Primaloft insulated, waterproof. I only took them down to -4 F, at which temp, and a lot of 10-35 F riding, my feet were toasty warm with thin smartwool or cotton socks. As somebody with diabetic neuropathy, I have to protect my feet. These work! As in, I can't tell when my feet are cold, except by taking my socks off and feeling them with my hands. So I would do this after rides of 3-4 hours, and not even a cool spot.
And you can walk in them all day. They feel like slightly heavy tennis shoes. (Except your feet will sweat indoors.)
They are short enough top-wise that they don't impede your pedaling motion. If you live near a metal shop with talented people, they could easily fabricate a steel insole and convert them to SPDs clipless-compatible, if you wanted.
Not absolutely cheap ($140. maybe $80 in the spring + maybe $30-50 to go clipless or cheaper DYI), but still less than winter cycling boots, and far warmer because they are designed by winter-sports experts, as opposed to warm-weather shoe experts whose marketing research shows some people (but not many) wanting to ride in temps around freezing, or somewhat below, but only a miniscule "not enough customers to justify satisfying" segment looking for frigid sub-10 F gear.
For example, Lake's CXZ and MXZ 202's ($269) use Thinsulate. A marvelous t low-bulk insulation in 1979, adopted widely by alpine sports mfrs in the 80s. But its performance was limited. Primaloft displaced it for frigid-temp applications. . Lake using Thinsulate today, as it does, is almost like a bike light mfr trying to sell a really-bright 30 years ago 100 lumen halogen headlamp for $279. Lake, and other bike-shoe mfrs aren't thinking about cyclists needing something for really cold temps. or people with very-cold-sensitive feet.
This is why you see comments by serious ice-bikers talking about using Sorels and other PAC-type boots. I'm suggesting a "higher tech" boot that is worth looking at. Depending on your shoe size, TNF Storm Summit will work with clips, and if you have size 12+ feet, PowerGrips. Or with mods, SPD is doable (or road pedals, if you don't want to walk around much).