Ah yes, I know which sleeves you mean!
I've never really liked folders and have always used card albums. Folders are too bulky and take up more room than is sometimes needed. Albums are just like books. Stick in the bookcase and you won't even notice it's there!
They come in 4 and 9 card pages sizes! ^o^
You can get some trading card albums off ebay.com.au after a quick search for "trading card albums"!