I currently have six binders devoted to J-pop photos, cards, and the like:
1) Assorted J-pop ephemera: Non-H!P autographs, set lists, photos, postcards, flyers, etc. and H!P ticket stubs, postcards, unofficial photos, sheets of stickers from photobooks, etc.
2) H!P trading cards
3) Photocards from CDs and DVDs (mostly H!P) and trading cards from H!P photobooks and the H!P official shop
4) H!P autographed cards and photos, official photos purchased second-hand, and some bromides
5) Official H!P photos purchased new, 2006–09
6) Official H!P photos purchased new, 2009–12
I need to buy some more binders, though. Most of my old-school Morning Musume。bromides (Parts 2 and 5 complete, Part 3 nearly complete, Part 4 about 2/3 complete) are not yet in binders, and I will also need another binder to house the huge lot of Yaguchi photos that I got dirt cheap on YAJ, now en route from From Japan.