LED's
Driver option 1
Driver option 2
~ $60 for the LED's and drivers. I've got tons and tons of heatsinks laying around so I'm not too worried about that. I'm still not sure about the optics but prices look to be less than $5 a piece.
So I'm looking at $80 or so for both high and low beam. Cycle Gear has HID kits for $55 a piece right now, but to properly do that I'd also need to get some projector housings. Those look to be about $70 for 2.
LED's = ~$80
HID's = ~$180