You are paying extra for a low-CAS kit with the G.Skill. That's why the price is so near the 8GB Corsair kit price.
Corsair and G.Skill are both excellent quality memory manufacturers. You can't go wrong with either one. However, as jaquith stated, the low-CAS G.Skill kit you linked is 1.65v and not recommended for Sandy Bridge CPUs.
If you can purchase by August 8th, I recommend this killer deal: G.Skill 8GB (2x4GB) 1866 CL9 1.5v kit for $65 with promo code
Otherwise, I normally recommend 8GB (2x4GB) 1600 CL9 1.5v kits of:
G.Skill Ripjaws X