I bought a sealed dualshock 3 and it's genuine (tested with MGS HD collection) so I figured maybe it can help you as a reference when looking for original ones online :
Restored PlayStation 3 Dualshock Black Controller (Refurbished) - Walmart.com
How to Spot Fake PS3 Controllers, DualShock 3 - YouTube
Amazon.com: PlayStation 3 DualShock 3 wireless controller - Metallic Grey : Video Games
How to Spot a Fake PS3 Controller Before Opening the Packaging - YouTube
Genuine Original PS3 Playstation 3 Wireless Dualshock 3 SIXAXIS Controller | Lazada Singapore
Official Sony PlayStation 3 PS3 Controller OEM Original Authentic TESTED | eBay
10x Ways to spot Fake PS3 DualShock 3 Controller including Packaging (Before & After Buying) - YouTube