To comment on the 4-5-03 posting. You won't find a ARC
D-79A for less than $1400. These units are extremely rare.
The D-79B and C models generally go for around $1800 to $2500 (if you can find an owner willing to sell one).
ARC made about 200 total units of the whole D-79 series and like the D-150 they are collectable units which command a high price by collectors.
A nice ARC amp that sell for less than $800 is the D-70.
It's bigger brother, the D-115 can be purchased for around $1100-$1200. I've owned both of these amps and they are excellent. These amps are fairly common and you will see one or two every month for sale.