> They, and only they, will have the Apple Hardware Test suite that is appropriate for the computer you are buying.

Apple has posted "Apple Hardware Test Images and Information" for various older Macs here, and I believe Bensheim's MDD G4 is one of them.

(In offering the same AHT image for multiple Macs the article apparently puts to rest, to a degree, at least, the belief that AHT discs are unique to the Macs with which they ship.)

In a different vein, you forgot to mention that original discs include bundled software that will be lost in the event a reinstallation with retail discs becomes necessary.

The new Great Equalizer is the SEND button.

In Memory of Harv: Those who can make you believe absurdities can make you commit atrocities. ~Voltaire