Although the going price on the auction site seems to be about $100, an AU-D5 would have to be PERFECT for me to give up $80 for it.
I bought a nice AU-D7 last year, and overhauled it completely. Coming from an AU-317II and AU-717 overhaul perspective, I didn't think the AU-D7 sounded as near as "full and rich" as either the 317II or or the 717 and it sure wasn't built as well as the older AU units. That might be comparing apples and oranges, but that's what I have experience with - I even liked the sound of the Sansui 771 receiver better than the AU-D7, which is the only other Sansui I've overhauled - that unit had such a warm mellow tone that I hated to see it go.