I had the xenon lights added to both the main light and the passing lamps on my road king (blue bulb, white light). The main headlight, on brights, is far brighter than anything I have ever had (imcluding cars). I can ride 80 mph out on the desert highway at night and not outride the light. I do not remember the cost, but not $500. maybe 200 or so? I dont remember it being 500 even including the passing lamps. I believe they 1st changed the headlight bulb bucket to accept a removable bulb, plus the HID bulb. (not sure if this is the same kit refered to above, I got the idea from JimmyK several months ago).
On my other 2 bikes (w/o passing lamps) I have added PIAA lights on one and MOTO lights on the other. Both are excellent. MOTO lights has recent adds for Harleys, fit on the crash bars, although a Super Glide probably doesn't have one?
I would absolutley agree w/ Thealien that the 1st step is to get the xenon headlight. Then add more if you like.