With the damage that marker has seen you would be lucky to get $250.00 and I think that was a pretty good offer(on your part).
One in average condition usually gets about $350-400. Looks do and will play a big part in your sale...With the feedtube munched up like that I would question the overall condition. Good luck with your sale, but you may want to lower the price.
"I wish simply to be a decent person, yet I will always fear the retards" -Brian Hindt(geech) MCB Moderator Kidney Machine