On sale from £52.99. For some reason on the Xbox store it is £31.79 however on the Windows 10 Store app, it is listed as £29.99. So if you only buy digital downloads, this is the cheapest it has ever been. It may be cheaper on disc, but this is the cheapest in digital format. I only buy digital games now so I don't need to constantly swap discs when steaming to my laptop.
I repeat, buy it from the Windows Store app. Its a play anywhere game so when you go to your Xbox store, it will say you own it and can install it on your Xbox One.
I just bought it. It actually cost me just over £23 as I bought it using £30 credit I bought from CDkeys at a discount.