Thanks for the responses guys. I spoke to Foto Riesel a few days ago and they didn't stock the sleeves I want. Vanbar don't have Printfile stuff listed in their online shop, but maybe worth a call...
Andy, yes I have been punching holes in another lot of sleeves I bought from B&H. So it is certainly an option. I was just hoping that someone around here might stock the pre-punched ones, as it would be one small job that I would no longer have to worry about. Given that the multi-punched sleeves are actually manufactured by Printfile, and are presumably useful to quite a few people, it surprises me that they are not more widely available... Oh well. Might just have to keep punching my own!