I'd think that a lot of the quality in elk stag would depend on the ethics of the grip maker. I've been known to wait extensive periods for quality elk stag grips. Pieces big enough for Bisley grips must be hard to find. My patience has resulted in my receiving elk stags that are virtually as dense as any Sambar I've ever held.. I've also seen elk stag that look like 100% pith. Let your grip maker know what you want and that if he is willing to look for the right material for you, that you are willing to wait to get it..
I see elk stag for $100-$150. This mongolian stag is $250 and Reeder has the best prices on custom fitted grips I've seen..