It becomes a bit more confusing when it comes to pricing. The SRAM rear derailleurs cost more on average than Shimano. The X1 and GX rear derailleurs cost more than XT. The X1 around 100 more than XT. Same with the cassettes. All the XD cassettes cost more than the XT. The GX shifter costs a bit less than XT. X1 is roughly the same cost as XT.
The way I look at it is if you go Shimano, buy the complete group. If you go SRAM piece it together to get the best cost to performance.
If I was to put together a "working mans" SRAM group:
Shifter: X01 or X1 if on a tighter budget
Derailleur: GX
Crank: GX (with the removable spider) or X01 (to help with weight)
Cassette: SRAM 1150
Chain: X1
I recently put together a Banshee Spitfire and cobbled together my SRAM 11 speed kit from free, used, and new parts.
Shifter: X01, new ($90)
Derailleur: X1, new from friend ($100)
Crank: XX1, used ($150)
Cassette: XX1, used ($0)
Chain: X1, new ($20)
My GF's bike has a full GX group and it all works together pretty darn well. It felt better than the XT and XTR bikes I demo'd before she got her 6Fattie. The Shimano shifters felt real tight compared to the SRAM.