Actually I wanted to buy the cable in the media market. There this was but 15 in my opinion extortionate! Moreover, I had been told there, that it is impossible to provide a graphics card with a SATA power cable. Nevertheless I took then buy such a cable, so I thought that 1 is now not the world. And the practical test just showed: you can run graphics cards via a SATA power cable!
For 1, the cable was really cheap and it does the job perfectly. The shipment was 7 days a bit longer, but that was not so bad. I am really very happy with my adapter cable!