I am seeing them show up at Cabela's and Academy. For example, yesterday, Academy had 3 on the shelf at 1030 in the morning but were gone by 1430. They had 2 DPMS and 1 Windham and the guy said that only 1 person was at the store at 0630 waiting to buy. Same is at Cabela's according the one of the gun guys running the nics. Fewer and fewer folks waiting outside for them.
To build a real quality AR, you will be shopping and hunting down parts and maybe the gun show has them... You'll have to weigh the costs to build versus buying one. the prices are going DOWN every day on the two popular gun auction sites. I remember when DPMS Oracle were trading for $1,850 and you could buy them at brick and mortar for $749. The Elk Castle has the same ones now and asking for $2,195.