You are going to get me in trouble since i didn't add everything up and told my wife "it will just be a few hundred".
... but.. $500 seems about right.
$140 for the Aluminum w/shipping (i ordered Black which is more $$)
$80 for a genuine E3D v6 hotend.
$50 for the motors.
$40 for the nuts/bolts (keep an eye out for coupons from Mr. Metric)
$40 for heatbed + Aluminum build plate.
$25 for Linear Rails
$20 for the Arduino w/Ramps 1.4 board
$20 for PSU
$100 for bits-and-bobs (gears, GT2 belts, bearings, end stops, wires)
I didn't order anything from China like the 'Bill of Materials' recommends. You could definitely get that price lower by ordering some of the parts from China but i don't like to wait. You could also save a large chunk of $$ by going with a lower cost hotend to start with.