Ribble Cycles have the Mavic Yksion Pro 2 UST tyres in both 25mm and 28mm sizes for just £20, down from £54. I held off posting here because I thought it was a glitch and they wouldn’t be in stock, but the order shipped today so I presume it’s genuine.
https://www.ribblecycles.co.uk/mavic-yksion-pro-2-ust-tyre/#pid=80424
They’re really good tyres in my experience, having put over 10k on a pair over the last two years. Not super-fast but sticky in the wet and cold and great puncture resistance on shit roads (unless you’re dozy enough to gash the sidewall on the edge of the pothole 😭).