Jason, there's no specific "SACD/DVD-Audio Cable". As Jack and Peter pointed out, this is simply transferring analog signals over three feet or so and any inexpensive "RCA" cables(not necessarily heavily shielded 75ohm coaxial)such as are often included with players should be entirely satisfactory.
As far as the speaker cable, get it at an inexpensive online or local source such as Home Depot. A behind the wall installation should use cable rated for that type of installation, not standard speaker wire, to keep the building/fire inspectors happy.
