Cold extremities often are the result of losing too much heat from your head. I wear a rabbit fur hat pulled down over the ears when I am sitting stationary and it's very cold (Ohio cold, ~0 F). That way I can get away with boots with just 400 g Thinsulate in them. They are Red Wings, underneath which I wear merino wool socks, two pairs. Try getting a warmer hat before spending time/money on boots.
I lived in northern WI for 6 years and Mpls. for 4 years so I do know cold. I have been out walking in the sunshine in -62 F indexed.
