Some blank CD-R disks are rated for burning at 4x speed. ProDirect probably has a favored brand which they will recommend, since many good brands are available. Sure, perhaps it is safer to use a name-brand disk, but they are more expensive. Maxell send us some generic disks that we burned at 8x speed. Verbatim, for example, makes DirectCD disks rated for 12x burners.
Paper is more economical.
You are paying for the jewel cases and the packaging. Buy in bulk and save. You can also save by asking for the newer 700 MB disks.