Cobb got back to me today the sway bars. Here's their response, copy and pasted:
"Hello,
No worries at all! It's always smart to shop around and find the best solution for your application.
We currently offer Whiteline anti-sway bars. While both Eibach and Whiteline are extremely reputable, these particular products in question are constructed differently and have their own pros-cons. The Whiteline anti-sway bars we sell are solid, whereas the Eibach bars are hollow. Here's a great tech write-up on the differences between the two construction methods. Either way you go, I'm certain you'll be pleased and see a dramatic difference in performance versus your stock application.
If you have any other questions, please don't hesitate to let me know!
Thank you,
Matt Bryant"
So I guess that explains the price differences between their's and TireRacks. Hope this helps!!
They provided a link also to a write up comparing the two types of sway bars.
http://www.whiteline.com.au/docs/bulletins/Hollow%20vs%20Solid%20Swaybar.pdf