Sorry Sab - can't help you.
Unless someone's got one, I guess it's a case of keeping ringing those dealers.
Fausto posted up that he'd had good experience with
InMoto and
Speedaway carry a reasonable stock too.
I guess you've tried
Aprilia Yorkshire as I presume that's where you copied the parts diagram from.
The number of times people post up about missing wheel spacers - I think they're special ones designed to hide the moment your back's turned.
Perhaps we should get a stock of the various wheel spacers and hold them on the forum - that'll probably guarantee that nobody loses one ever again!
..... don't suppose anyone works in a machine shop or has easy access to one that could run up a small stock of spacers for the front and rear wheels?
Just a thought.