Aero Precision’s Weekend Special is their M4E1 16″ .223 Wylde Complete Upper with 15″ KeyMod Handguard for $399.99.
I own one of these M4E1 uppers and I find it to be very rigid, easy to work on, and relatively lightweight. The 16″ stainless steel, .223 Wylde chambered, 1 in 8″ twist barrel included with this upper is manufactured by Ballistic Advantage and has an good reputation for accuracy. This is a lot of upper for the money, especially if you are in the market for a light precision AR build.
Check out the M4E1 16″ .223 Wylde Complete Upper with 15″ KeyMod Handguard at Aero Precision. The sale price is available through the weekend. Be sure to choose the 15″ KeyMod handguard option to see the sale pricing.