To be honest, I just use what ever Tesco, or Staples have. They keep the stills in order, and you can get a couple of hundred stills in each.. Cheap too, I worked out some of the more expensive options, and it would have cost a fortune to put all mine in. I have around 3000, so cost has to come into it..
They are just ring binders which you put pockets at the appropriate size in. The Binders are about 3" or so thick..