If you don't mind using platforms, perhaps with Power Grips, the North Face Storm Peak II boot is great. A pair weighs about 2 pounds. Totally waterproof. Has a D-ring for gaitors (I made neoprene ones from an old pair of zip-up scuba booties, and they keep the lower leg/ankle area very warm).

It's insulated with Primaloft, the new synthetic down substitute. Rated to -25 F (-32 C). I've ridden at +6F, -12 windchill, with only thin cotton socks, and feet were very warm.

I got them at REI, which has a full-satisfaction refund policy, even after extended use. TNF makes serious gear for outdoor enthusiasts, and these boots should hold up well.

Price: $130. Size 14 is a tad roomier than my Shimano 122 50s.