Transparent MusicWave Super

Does anyone know the used price for 8' spade terminated MusicWave Super XL biwire cable? Condition is 8/10

I bought the exact cable used approx. 4 months ago and paid 500.00. I thought that was a good price to pay. I would grade mine either 8 or 9 out of 10.
$600 should be about right for the biwire version. Anything more is over priced.