IMO eBay the Kingston DDR3-1333; I'm not aware of any 'Value' set with CAS 7. In other words, don't mix: 1. Problems Mix-Matched Frequency, CAS, Density, IC's, etc. 2. It will kill Dual Channel, 3. ALL sticks will be running at DDR3-1333 and whatever LCD (worst) CAS per all sticks.
The G.SKILL Ripjaws X Series 8GB (2 x 4GB) DDR3 1600 F3-12800CL9D-8GBXL is $50