About $800 for the upper, with sights and red dot yet to buy. I have about $350 into the lower. I figure about $150 in tools and supplies (grease, loc-tite, etc), which I won't need to buy next time out.

As far as time, the upper went together in a few hours. The time-wasting was during extra trips to the hardware store and the gun store, as well as looking for parts online.