The only thing I've ever sold online was an item from the MMO Everquest. I ran a top raiding guild on my server and had just gotten a really rare end-game item but I was coming up short on rent so I jokingly offered to sell it to some guildies. None of them took me up on it, but one guy had heard about someone who was looking for the item and willing to pay, so I chatted him up and wound up selling him the item for $250. I was super nervous about it but everything went great.