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 :
Sony PS3 Dualshock 3 Wireless Controller (PS3) - buy at Galaxus
Bluetooth Wireless Dual Shock 3 Six Axis Game Controller for Sony PS3 PS3 Accessories - Newegg.com
De la PS1 à la PS5 : (re)découvrez 5 générations de manettes PlayStation
PlayStation 3 SIXAXIS Dissection and Dual Shock Comparison - IGN
Sixaxis vs DualShock 3 (DualShock 4 vs DualShock 3) – Technology – Purplepedia