I can recommend the Focal Elite 1 meter rca as an upgrade ( yes I have compared with my Wiim pro cables 1 year ago ) .I am very happy with the quality of the supplied cables. Way better than what other companies supply, if they do.
I have never spent more than £20 - £30 on a cable and now I would never even consider spending that much.
IME they make no difference at all.
I now tend to buy something from Kenable or Amazon Basics, just to get something a bit more robust.
Although I agree that a lot (the majority?) of people who buy the Ultra would "upgrade" their interconnects. So the decision to supply cables is a bit of a strange one.
Personally I'm using what it come with.
Cost about 25 dollars.
Most cables thats more expensive are worse than the stock ultra rca cables ( I have tried many )