I've always been interested in Buells, they had some real innovation in their time. Super steep rake angle and mega short wheelbase(!) Oil in the frame for packaging and the rim mounted disks allowed for a lightweight front wheel as the braking forces are transmitted directly to the rim and tyre..such a shame the company didn't keep going...
I'm thinking any replacement discs, wheels, calipers or pads are either unobtanium or ludicrously expensive.