Corsair XMS2 4GB (2 x 2GB) PC2-6400 DDR2 Memory Kit for $14.99 shipped for in-store pickup only after submitting this $25 rebate. Here is a screenshot for your reference. For the technically inclined, this set of RAM has a voltage specification of 1.9v and operates at 800MHz with 5-5-5-18 timing. More information is available here. Alternatively, it is available here for $17.99 shipped after a $25 rebate.
This post has been revised.