If I hadn't stopped a couple of years ago, I would probably have that kind of collection as well. I used to have original copies of 'Saw You Drown' & 'Rain Without End', some Katatonia vinyl, a promotional copy of DO and a bunch of T-shirts, but I sold pretty much everything, except for that "Once We Were Gods"-T-Shirt...which I think I haven't seen in any of the pics.
And of course I still have pretty much all of the CDs, but I just figured I don't need to have everything. I'm glad you collected all this stuff though. You should open a Katatonia museum some day.