I'm not sure if you checked around, but there are 3 nicer copies for $300, $337.50 and $350 available on abe. There is even one with a signed silkscreeen for $450. Not trying to screw up your sale (people on this forum are well researched anyway, so they know this), but this book in the condition that you have did not sell for $600 even in the high times. If you are really interested in selling this, you are looking at $200 (if those are stains on the front of the book), or $250 if they are just camera glare.
Bill