Delta Tech Lighting Makes HID Light Bar that is same as OEM Light bar (meaning same 4 light layout with same Lens and Set Up)
Maybe you can call them and ask if you could buy their bulbs and ballast. They put their Ballast inside the bar , so not sure if its special size or what.
http://deltatechindustries.com/lightbars_hummer.html
http://deltatechindustries.com/site/01-9064-HID4