A friend has a Aerotrim < link > on his KTM990. They're South African and he thinks he may have imported it direct from there but suggests e-mailing them to see what they suggest.
It cost £40 and he's very happy with it as he can now cruise almost as fast as me on my GS BMW
An alternative is to make one out of an old visor as I did for my low-screened BMW R100RS.