I have ordered an Addax GPU Upper and am looking for suggestions on a reasonably priced buttstock assembly to install with this upper (links would be appreciated).  I really like the look of the Addax GPU, here are the specs:

Ion Bonded Addax Gas Piston Upper assembly
DD Omega rail, 7.0
YHM 16" - 1:9 twist ratio - chrome lined barrels Chambered in 5.56 NATO
Flat top upper receiver assembly with M4 feed ramps
Del-ton BCG Semi Auto + Charging handle
A2 flashider

I will also need some sights, any suggestions on these?  Being a newbie, please mention if I need any other parts to install your recommendation.

Thanks,