Try Triumphant M/C's, a UK-based Triumph breaker, if you want the genuine article (some Honda VTR 1000/Blackbird clips-ons are compatible too). I enquired about a pair last week for my 'Tona 12 and they were available, ex-stock.
http://www.triumph-ant.co.uk
I've used them for bits for my 'Tona 12 before and they're a good bunch of lads!
Cheers...
Addict