Just for those who want a slimline type case, this is what I now have for the TNG seasons 1-3 and DS9 S3:
$7.50 for a box of 10 from these guys:
All I have to do now is print the labels for them that I downloaded from these guys:
They work beautifully, and hold 8 discs each. I stored my boxes away just in case I needed them. The TNG boxes weigh a ton! I was holding one after I removed all the DVDs and you could have swore on a stack of Bibles that all the DVDs were still in there. They are very heavy.
These are pretty cool cases, they're along the lines of what I was talking about, except that they are the width of a single DVD case. I find that those or the ones you posted feel better, for reasons you and others have mentioned, easier to get them, store better, etc...