I think these are the official option: Corsair CP-8920202 SF Series Premium PSU Cable Kit
I'm going place an order for these pretty soon and at $40 retail, a lot cheaper than custom options. These really should've been the set that was included with the SF series to begin with..
Yes, I agree that these should have been included with the PSU as standard.
There are still 2 things to take note. One is, the length of these cables is just the same as the current stock cables, meaning they are likely to be too long. Another is, I reckon the price (US$40) for this cable set is still a little expensive. On one hand, it is cheaper than other custom options. But on the other hand, those other options are run by small 'boutique' shops that, with their low volume and turnover, have to charge higher in order to really make a profit and survive. But, Corsair is a large company. Well, maybe this is why they do not charge as much as the other custom options. But still, $40 is half the price of a SF450 already. It is a little hard to accept that half of the value of a PSU belongs to the cables.
When the time comes for me to get cables for a SF600, I will head to Aliexpress and Taobao to buy cheaper+shorter alternatives.