Ummm, shoe boxes will do quite nicely and don't cost a dime if you strike up a friendly conversation with one of the fellows at a local shoe store...
Looks like Peter's suggestion best for me: very cheap for ordinary boxes of the right size, not bad (80 bucks for 10 108 CD boxes) for "storage boxes" with readily removable lids.
Scavaging suits me, Rl, but the likely heterogeniety of one's haul might make packing and and stacking enough of a headache to justify the cost of "store bought" boxes.
Xtremefidelity's suggestion of special jewel sleeves which cut the size of packaging by 75% looks like a great space saver, but as I live in the middle of the country and have a fairly modest collection, I don't need to incur the expense.
Good listening indeed! :)