I’ve read that HDMI cables for i2S should optimally be no more than 1 foot in length (i2S was originally developed for internal connections inside a component so not designed for distance), and several people also said they didn’t hear big differences between cables in this application. As a result I started with this 6” cable from Monoprice — the shortest one I could find — that costs under $7 in my HeadFi rig and still got significant benefits switching from SPDIF to i2S. I’ll eventually upgrade just to try something better, but honestly I’m very happy with the sound and am in no rush to throw more $$$ at it right now.
That said, many people have spoken highly of this DH Labs cable for both sound and relative value, so this might be a good option if you’re willing to pay more. I just don’t like that the shortest version seems to be 1.5 feet that wouldn’t seem to be optimal for i2S purposes, and I find myself wondering if the benefits of a better cable would be largely offset by the significantly increased length.
Hope this helps, and best of luck.