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 :
Amazon.com: Dualshock 3 Wireless Controller for Ps3 Charcoal Black : Video Games
How to Spot Fake PS3 Controllers, DualShock 3 - YouTube
Is this a real Dualshock 3 controller? Seller claimed to be genuine : r/PS3
Is this a real Dualshock 3 controller? Seller claimed to be genuine : r/PS3
Official Sony PlayStation 3 PS3 Controller OEM Original Authentic TESTED | eBay
Amazon.com: PlayStation 3 Dualshock 3 Wireless Controller (Black) : Video Games
10x Ways to spot Fake PS3 DualShock 3 Controller including Packaging (Before & After Buying) - YouTube
Sony PS3 Original (official) Wireless Controller Pad - DualShock 3 -Metallic Grey Color | Jumia Nigeria
Spotting a Fake PS3 Dualshock Controller
PS3 Joystick / kontroler DUALSHOCK 3 WIRELESS, original Sony
Sony Ps3 Controller
How to Connect PS3 Controller (Original/Fake) or Dualshock 4 to your PC | Kunmi's Space
With fake DualShock 3 controllers flooding marketplaces, genuine unused ones are getting expensive! I'm glad I have a few in my collection : r/PS3
Genuine Original PS3 Playstation 3 Wireless Dualshock 3 SIXAXIS Controller | Lazada Singapore