The M1.5 @ $500 in is the ballpark of what hifi shark says they have sold for...BUT....why buy a potential problem (10 years old) when you can spend less and get a brand new amplifier that will sound as good and probably better, easy resale if you ever want to resell, tons of power with L/R gain controls that will allow balance.
Crown XLS 1502 DriveCore™ 2 Series power amplifier — 300W x 2 at 8 ohms, 1,550W x 1 at 4 ohms bridged at Crutchfield
Crown XLS 1502 DriveCore™ 2 Series power amplifier — 300W x 2 at 8 ohms, 1,550W x 1 at 4 ohms bridged at Crutchfield