There's an entire section in The Knife Exchange here at Bladeforums for selling automatic/switchblade knives. You can find it by clicking on "Knife Exchange" in the upper left corner of the screen under the Bladeforums logo, then click on "For Sale By Individuals", then the automatic/switchblade section. But you need to purchase a Gold membership to sell things on this forum. To read more about becoming a Gold member click "Paid Subscriptions" in the blue banner across the top of the screen.
Not being a Gold member it would be against the rules to offer/advertise anything for sale, or solicit offers from others.