Yukichigai,
Do you mean the box type or the type that opens like a book?
If you mean the box type, the cheapest & most usefull, I think, you'll find is a Sterilite Show Offs "CD" Case.
You'll find them at Wallmart, Target and some Dollar Stores for $2.00.
Yes, $2.
Wallgreen's has them for $3.
They're in the housewares/storage area.
They're not in the computer section or the music section.
They include a carying handle on top.
Most CD cases don't have a handle.
Instead of carrying, balancing it from underneath, you can easily grab the handle and head out the door.
The top latches onto the case on two sides.
You completely remove the top to access your CD's.
You can easily flip through your CD's on your desk or in your lap without a top to flop down on you.
They are stackable.
There are no dividers inside, just open space.
I've used them to hold slim jewel cases.
I've been able to fit 3x as many paper sleeved CD's than slim jeweled CD's.
It's waaay better than the $10 on sale item I got at CUSA.
The CUSA item included some vinyl, tyvec double sided sleeves.
I think It's a better deal to get the $2 case and a 100-pack of cheap, paper sleeves for $6.