Sig Sauer P320 XTEN For Sale Online The Sig Sauer p320 XTEN rifle is a revolutionary new weapon that will change the way handgun owners use their guns. It is modular and optics-ready, as well as equipped with night sights. The prices will be between $600 and $1,200. Sig Sauer will offer accessories for the rifle in future. You may not find a suitable accessory for this gun right away as it is still relatively new.