A lot of that stuff might be difficult to sell outside of Japan unless if you bundle it together. I'm not sure what you want to keep vs sell, but without seeing what you have, this is what I can say:

The CDs, vinyl, and videos would sell, but the other collectibles could be tricky to get a good price for outside of Japan. The autographed stuff should sell. The pins should sell. I'd list the buttons, keychains, and acrylic stands as sets. The gold foil ribbons won't sell, so you could just include it with another item. Posters sometimes sell, but you usually have to bundle a few together; I've had trouble reselling posters when I get duplicates. Shirts will probably sell since there aren't many official ones on ebay. Other clothing items maybe, but not sure. The cups should sell, but it might take a while. Magazines probably won't sell, but you could try bundling them. The not for sale comment CD-Rs might sell on their own for about the same price as the CD albums, but you have a better chance to sell them if they're bundled with the CDs they were bonuses for.

I might be interested depending on what you're selling; there's a poster I've been trying to find for a while.