Not sure about Ridex, but Febi make them, and I fitted a pair a couple of years ago and they still seem very good. I did try a pair a few years ago (Coved lockdown era) from GSF, but the bushes seemed to degrade pretty quickly and showed up as an advisory after a few years.
From memory, the Febi ones cost £37 each delivered from a UK supplier on EBay.
My experience of Febi (Bilstein) replacement parts has always been very good, so I'd recommend them.
Expect to have to get your tracking checked afterwards, as every part you fit in that area will be always be a tiny amount different from what it replaced, and a tiny amount in that area can lead to tyres wearing strangely and more expense.
These day, I only have tracking done on one of those Hunter laser machines, as I find the extra expense of the check is well worth it for the extended tyre life.