My Disney books are always HUGE, and I always need way more refills than they have in the book. After many, many times of trying to match the refills (Pioneer had the ones that were closest--at least in what the stores here sell), I read a thread where a DIS-er said she took the WDW page protectors out, and just bought however many she needed (total) at an ACMoore, or Joann's, or Hobby Lobby. . .somewhere they were on sale. Then, they all matched. That is what I've done for our last 2 trips. I figure that by the next trip, I'll have enough WDW protectors from all of them combined that they'll match!
Good luck with your search!