Just did my first AR build for $1300, picked it up this week. <-- I bought a complete lower (400), and separately bought a complete upper (900), happily paying a little more for piece of mind. I didnt feel comfortable hunting for individual upper build pieces esp. in light of the BCG issue.
LGS is prob one of your better bets. Online, the speed on the forum/broader internet community buying anything that comes temporarily 'in stock' is amazing...
ammo - for new AR guys like myself, 60c / rnd seems to be the going rate. Which I am somewhat comfortable with, though historical prices are painful to hear about.
Everyone has an opinion, but i think the AWB will not happen. CA is different bc the deck is stacked against us.