Used the $10 & free pts code I got from BL2 -- preordered AC3 and added 1600 pts to my cart:
$59.99 + $19.99 = 79.98 - $10 off - 19.99 off pts = $49.99 + tax = $53.11
Plus another $10 off & 1600 pts after AC3 ships (will use it on Halo 4 preorder)

ShopDiscover has 5% or Fatwallet has 4% cash back at MS store

The free 1600 pts code only works on the electronic version (didn't let me use it if I tried to ship it) -- I wanted the actual card so I could sell it

Got the confirmation email after 30 mins which included the 1600 pts code