That's interesting... I contacted Nitron after the JCW Challenge car was announced to see if was available to buy the suspension and they told me that they have an agreement with Mini that they were unable to sell the kits separately for the Mini F56 making it exclusive to the JCW Challenge car!
I noticed on the UK website that the kit is still not listed so wondering if the agreement is only UK based (as JCW Challenge was only available in UK)?
It is apparently only very recently becoming available. They're taking orders in the UK, but the product is apparently a few weeks away. It isn't the exact suspension from the challenge, but close. Apparently this kit has wider ranges of adjustment, but the same spring rates. I'm sure the top mounts won't say John Cooper Works either.
For a premium of more than $500 over even the KW Clubsport, the price is a tough pill to swallow.