I don't think you can obtain true HID for $100, maybe some of the blue/white tint bulbs and a upgraded harness, but true HID is going to cost a lot more than that.
I haven't used this device from BriteBox I am running their Turbo Lifesaver and it is a excellent product. I am also using the upgraded harness from GOS so if you are worried about the quality of what they sell I can tell you they are first rate.