It’s not really a cost saving I’m hoping for with a 12sp GX full pin, it’s a full set of steel cogs.
From a mfr POV I get that SRAM will see a saving by using a part they already have rather than stamping a steel 50T to pin on instead, but I do suspect the real reason they don’t want to do this is more about the life of the cassette. I know lots of riders who decided the GX was light enough even if it wasn’t the lightest available cassette simply because of the all-steel goodness…
On cost, the GX 1150 was £70odd when 11sp was the best game in town and it had the sales volumes, but you’re doing well to have much change out of £90 for one now I think. and that’s still discounted from RRP so the cost of the Eagle GX while obviously not cheap isn’t quite the ‘double’ it looks like on the face of the earlier comparison.
I’ll be surprised if 12sp XT when it happens in 2020 or whenever isn’t cheaper than SRAM Eagle at street price once volumes are taken into account. Until both products are in to play with it’s a redundant comparison really. It will pretty much put the ‘you need a new freehub’ thing to bed as both systems will need something newer than the old Shimano FH.