I dont know why you would compare the 6.8 to the 30-06? The 5.56 is going nowhere anytime soon. The cost would be unimaginable. Never say never, but the only way to get the cost down is if it was adopted by our military. Right now 30-06 ammo is around $14-$16 for 20. A box of 6.8 is about 26.00. I am reloading the 6.8 and its costing me:
brass .55
primer .35
bullet .20
powder .11
Thats once fired brass, so $1.21 a round or $24.20 for 20. I am reloading .223 for $.30 a round or $6 for 20. You may not reload, but thats how we figure our costs. I dont know where you came up with it would be cheaper than the 30-06? You might want to read this:
http://en.wikipedia.org/wiki/6.8_mm_Remington_SPC
The 6.8 was developed by spec op guys not ammo or gun manufactures. Thats why I said it is what it is. I like the round alot, but it wont be cheap anytime soon. I think the guys that do like the 6.8 will be doing some great things with it.