I have bought some of those in the past from ebay, loads of Chinese manufacturers carry them.
Search for SFF 8088 to SATA on eBay and get a whole list of them. Have not had a bad cable sofar.
Works well and its easy to loop them back in via an open pci slot.
I will use the cards with Supermicro SC847E17 Chassis.
Using a Supermicro 2x SFF-8087 to 2x SFF-8088 cable. ( internal to external, i think thats CBL-0168L) to get to the back of the case
Then use short 8088 to 8088 cables to connect to the card.