I prefer to run the Wolf Tooth stainless rings, which last a whole lot longer but all I had was a 32 tooth one and it was just slightly too big and rubbed my chain stay with these cranks. I have a set of 3x M760 XT cranks that I use with the belt drive and those work fine with 32 teeth but the difference is these 2x cranks don't have any way to mount a ring on the outer side of the spider. So the 30 tooth it is.
http://www.wolftoothcomponents.com/collections/mountain/products/104-bcd-stainless-steel-chainrings
If you use an M8000 GS rear derailleur you don't have to do anything to make them work acceptably with up to a 42-tooth rear cog and it will work with both 10 and 11 speeds. Since it's only like $20 more than the side plates or a Goat Link there's no reason to bother starting with a 10-speed derailleur at all if you don't already have one.
http://www.jensonusa.com/Shimano-XT-RD-M8000-11SP-Rear-Derailleur
I was also wrong, Wolf Tooth is making a 45-tooth rear cog for Shimano 11-speed cassettes. I have no experience if it shift alright or not. I use a 40 and Kirsten a 42 tooth with the RADr cage modifications and it works decently. I just about never use the 40 but it's a bail-out in case. In fact I find I generally never use 36 or 32 either, but I've been riding single speed exclusively for about 6 months so I'm used to standing instead of downshifting.
If I was starting new, assuming you can reuse your cranks, the parts list would be:
RD-M8000-GS (rear derailleur) - $91
CS-M8000 (11-42, cassette) - $87
SL-M9000 (right shifter) - $106
PC-X1 (chain) - $31
Wolf Tooth 32-tooth front chainring - $60
That's $375 but with a little shopping it would easy to shave about 20% from these prices and use XT shifter to save another $30. So you'd probably be able to do a 1x conversion for about $300.
Adding the 45-tooth giant cog would be $90 plus then you'd apparently need to run Goat Link 11, which is another $28.
So you're looking at about $400 assuming you can reuse your cranks (which is /probably/ the case).
http://www.wolftoothcomponents.com/...cogs/products/45t-gc-cog-for-shimano-11-speed
Doing a 32t front and 11-45 would give a gear inch range of 20.5 to 84, which is pretty wide. That's the same granny as 24 front, 34 back. A 22 front, 36 back is 17.7 and to get this would require 28 front and 45 back in 1x. That would drop the top to 73.5 gear inches, the same as 32 front, 13 rear.
Ultimately it doesn't matter because until you run a 50 tooth rear you can't ever get back the big ring on a 2x or 3x configuration. You need at least a 32 tooth chain ring to even come close and a 34 tooth would be better. A 32 front with a 50-10 (SRAM) rear would be darn close to the same range as a 26/38 and 11-36 2x drivetrain.
The problem really going SRAM is the price.
X01 Eagle 50-10 cassette - $360
X01 Eagle rear derailleur - $220
X01 Eagle shifter - $127
X01 Eagle chain - $60
Wolf Tooth chainring - $60
That's $827 and then you still need new hubs with the XD free hub for the cassette.
There is another way to get a 10-tooth rear other than SRAM. One Up makes a little free hub adapter for Stan's and Hope's hubs that makes it possible to run smaller than 11 tooth rear cogs. But this whole thing is a kludge and IMHO not worth the trouble for one tooth. If you need or want the high end for road or downhill, run a 2x front.
http://www.oneupcomponents.com/products/minidriver
FWIW, at 90 RPM running 79 gear inches is 21 MPH and 100 gear inches (34 front, 10 rear) is 27 MPH. So losing the top 2 gears going from 2x10 to 1x10 is a pretty significant jump. In a 3x9 with a (42 front big ring/11 rear smallest) 110 gear inch top 90 RPM is 30 MPH, so going from 3x9 to 1x10/11/12 is losing the top 30% of your range.
