Replacement HISS looms go on eBay for anything between £250 and £500, so you could get hold of one, or perhaps try selling it on cheaper to someone who doesn't mind tinkering with that sort of thing.

Alternatively, it might be worth contacting these folks http://www.twiggersmotorcycles.co.uk/motorcycle-accessories/88-Motorcycle-Key-Services.html as they advertise a HISS replacement key service if you send them the ignition barrel. Never used them myself, so no idea whether they're any good or not. Keys start at about £30-£40 plus whatever work needs to be done to tune the blank to the ignition chip.

Good luck.

>> ex silens nox noctis <<