Have you tried chemical warmers yet? I've a handful of them but haven't had a chance to try them as of yet. I have heard the Lake winter shoes are nice, and they aren't as expensive as Sidi.
Chemical warmers are great, but they don't seem to work if it starts raining. Something to consider.
Sarah
When it's easy, ride hard; when it's hard, ride easy.
2011 Volagi Liscio
2010 Pegoretti Love #3 "Manovelo"
2011 Mercian Vincitore Special
2003 Eddy Merckx Team SC - stolen
2001 Colnago Ovalmaster Stars and Stripes