to be fair I think of this release the WiFi Cargo and Classic Mini completes will sell out really fast (last time is was within an hour) but variant frame kits should be around a while, maybe see if your local Omnium dealer is looking to get one in, or drop me a message if I can help
37mm with mudguards is the official spec, I’ve fitted 38s pretty easy
The completes are £1620 so I imagine based on the framekit/complete price difference on a Mini Max it’d be about £700ish for the classic mini framekit