The Auction option is a free service and all you have to do is sing up. The auction just like our classified section is not limited to scorpions. Feel free to put up any invert or bid on any. Signing up only takes a few minutes and again this service is FREE.
The Auction Site is... http://www.protokillers.com/arachnoauctions/.

You can post up your auction here on the classified section. And label it AUC instead of the usual FS or FT. So if I put an B. jacksonni up for auction my message might look a little something like this.

AUC: B. jacksonni
5 B. jacksonni at Arachnoauction starting bid $5 good luck. (link to auction here)