It really would depend on how much money you want to spend and how quickly you want them.
As far as myself, I did not want to pay $1400.00 - $1600.00, so I just kept looking for 2nd hand on eBay and other forums and got a nice set barely used for $800.00 delivered.
I would stay away from the HID kit.
As far as new, just google and price compare.
here are a couple sites I use:
http://e-partssales.com/Merchant2/merchant.mvc?
http://www.pelicanparts.com/techarticles/box_litronic/litronic_pg1a.htm