Corsair Vengeance 8GB (2x 4GB) PC3-12800 DDR3 Desktop Memory for $36.99 shipped after promo code EMCJHJJ78.  Here is a screenshot for reference.  Alternatively, it is available at Amazon for $36.99 shipped.  It features 9-9-9-24 latency at 1.5V, heat spreader and Intel XMP support.  Most places have this dual channel RAM kit for about $44.