If she can tollerate a bell-less collar, then there is an alternative.
The Liberator collar senses the inertia of your cats pounce and sounds an alarm. Because it's not making the noise all the time, and because it doesn't stop your cat stalking things, it should be much easier for her to adapt to. It's available here for �9.99:
http://www.petplanet.co.uk/product.asp?dept_id =38&pf_id=1252
There's more info from the manufacturers here:
http://www.liberators.com.au/pages/how.asp
Maybe you could introduce it to her for short periods of time over several weeks? You could try a cheap collar, to see if she can get used to the idea, before investing a tenner.
Several years ago I saw a slightly different device - it attatched to a normal collar and emitted bird-scaring squeaks in a range cats and humans can't hear. That would be my first choice, but I haven't been able to find it since so I've been eyeing up the Liberator for my two mogs.
The problem for me is that our cats bring in huge numbers of rats, mice and voles (usually live), and I want a collar that will prevent ALL hunting. Our vet suggested keeping them in at night, so they can't hunt when prey is at its most vulnerable (dusk and dawn) but that's only reduced the catches by about a third.
I'm nominating the CatBib for the award of daftest invention 2006. It's a completely mad idea only for the most tollerant of cats!
http://www.catgoods.com/testimonials12.html
The only other thing I have to suggest is having her spayed, which won't be much help if she's already had it done!
Good luck on your quest,
Fiona