Hi All, I have a Gray Matter case for sale in Orange County, California. It goes regularly for around $340 shipped, I'm selling for $275.
Gray Matter Economy Case
7 GPU
To gain credibity and also maybe catch customers you should take photos of the case next to your bitcointalk name and today's date.
Also hence the item is worth 275$ at your costs you have to offer some kind of guaranty for buyer, so escrow would be a good option too.