I used to go by anything that was worth over $5 would go in to a binder and anything less would go in to a 5,000-ct box. I don't pick up many packs or boxes any more so that rule doesn't matter for me as much any more.
I focus my PC on Ken Griffey Jr but I also collect Jay Buhner, Steve Largent and Ryan Bader. Secondary collection: Seattle teams & Univ. of Arizona