[Where can you order a modular 8-pin PSU to CPU Flat Cable?]

I am using an MSI motherboard requiring a 24-pin ATX power supply and 2 - 8-pin PSU to CPU cables. The Toughpower 650 only comes with one 1 x ATX 12v (4+4 pin) cable. I have been unable to find a place to purchase another 8-pin PSU to CPU cable in the same length (50-60 cm). Where can they be purchased? The modular usually come with so many cables I didn't think I needed to check the number of cpu cables needed and I'm can't steal the one off my old build yet until the new build replaces it.