You will be very lucky to find one.
AFAIK,the switchgear on the '04-'09 Tuono is unique to that bike and not fitted to any other Aprilia.The RSVR switchgear is different,...they have the mode button on the clocks.
You sure the switch is'nt repairable?I heard of one where the rubber cover got dislodged and jammed the switch up.