Where can I purchase an SLI connector?

I purchased a motherboard which features two PCI Express 16x mechanical slots.  The motherboard did not come with the SLI connector needed to connect two NVIDIA PCI Express graphics cards for SLI mode.  Where do I purchase this connector? 

The SLI scalability connector is included with NVIDIA SLI-certified motherboards and SLI-enabled systems.  If your motherboard supports SLI and did not come with this connector, contact the maker of your motherboard or computer for information on obtaining a replacement SLI bridge connector.