NiB BCG + 16" M4 barrel - $160 on Primary Arms

http://www.primaryarms.com/Kit-FZBCG-AMBARREL

Details from the page:

A completely assembled, ready to install AR-15/M16 Bolt Carrier Group. Kit includes six critical parts that are treated with EXO Technology, a revolutionary surface technology that provides permanent dry lubricity, radically improves the performance of your AR-15/M16 and eliminates the need to apply oil or grease to treated parts for the life of the weapon. All Fail Zero bolts are MPI tested and live fire tested. They do not do HPT, as they feel live fire is a better test.
A quality barrel priced to meet any builder's budget! Starting with ordnance grade 4140 Chromoly steel, this barrel is precision cut to M4 contour, reducing weight where it matters for a balanced build. The properly dimensioned 0.068" gas port is located for the highly reliable carbine gas system and is ready for your favorite .750" gas blocks. Chambered for 5.56 NATO and fully capable of running .223 Remington, this barrel features a 1:8 twist rate, ideal for a wide variety of projectiles from 45 grains up to 77! M4 feedramps and a durable phosphate finish ensure reliable feeding and long-term durability.