Trying to buy my first AR?

hi, I'm finding myself badly wanting an AR-15, but I don't know what I should get. I know i want a 16" Carbine with an A3 upper in 5.56 NATO, but all these different guns confuse me. should i start with a kit, or buy the gun complete? Should I order from a website (Del-ton, DPMS) or should i buy from a dealer? I'm on a budget of $1000, can someone point me in the right direction?