It looks like the best you can do is the MSI GTX 680 4GB Twin Frozr III. The Lightning is 2GB only.
http://www.msi.com/product/vga/#?fp=GeForce%20600%20Series&sk=Geforce%20GTX%20680
I would say that the Lightning is not worth it because in general they are specifically designed for extreme overclocking with maximum voltage applied. Since the GTX 680, even the Lightning edition, is voltage limited by the GPU with no exceptions, you won't get the same benefits out of voltage modding with the GTX 680 Lightning you might expect from past generations. In this case, the real benefit of the GTX 680 Lightning is the Twin Frozr IV cooler and the higher factory overclock. If you want 4GB, then the Twin Frozr III with your own maximum overclock will do just as well.