I've got my Vermeer S600tx for sale. Its got around 1100 hours with the reliable Kholer 25 hp motor. Comes with no attachments. Full service 35 hours ago. New front right idler pulley. Tracks around 40% left. Selling to purchase a new one. (tax purposes) $15,000.
You may consider trading this in if you are selling for tax reasons. Under IRS section 1031 "Like Kind Exchange" you won't have to pay income tax on the proceeds of the sale. Just a thought, good luck!