When I first starting to commute in the winter, I bought a set of these :-
http://www.rain-off.com/They work very well, if a bit fiddly to put on. Water and windproof.
Then on my commuter ('88 Magna), I added a set of these :-
http://knucklewarmers.com/These also work very well, but I still carry the rain-offs in case of really serious downpours. Water and windproof (except when things get extreme)
On my Valk, I fitted a set of these :-
http://store.valueaccessories.net/handdeflectorssetclear.aspxAgain under 'normal' conditions they work as well as the above. Wind and rain deflects very well.
Amongst my searches however, I did find a cheaper set of hand deflectors (but I did not buy these). Second one down - hand warmers... :-
http://www.vpaccessories.com/valkyrie_accessories.htm