Amazon was the place of choice when a friend bought some for his XL. He ended up with Mont Blanc bars for about £80, but I can't see any of those around that price; nearest are some Menabo bars for £85.
Brand wouldn't necessarily bother me; as long as the fit is right and the rating is sufficient, I'm a happy boy. The name on the things isn't necessarily indicative of quality or these sort of items being better than a cheaper alternative.
Before you commit, check the
reviews for whatever you're considering and also check the weight limit; some bars will be rated considerably
lower than others, so spend ten minutes doing your homework.
Just my two penneth!
R.