Be warned, the projector system is expensive and not too easy to do (we're talking around $1000+). If that's your thing, okay... but normal people aren't willing to spend that much for insignificantly better headlights. But hey... if its your thing...
EDIT: $1000+ assuming you buy new stock headlights to modify, which you should do instead of potentially screwed up your own or not being able to drive at night for 2 weeks if you send your own in to that guy (which isn't a good idea imo).
That is still high, unless you buy brand new lights from the dealer. Here is a break down of my hid retro so far. Note that other then the actual projector housings, everything is OEM componets, not China knockoff stuff.
Projectors, Bulbs, Ballasts, wiring - $360
Used headlights off ebay - $105
Misc. (dremel bits, foil tape, etc) - $50
Total (not counting my time) - $515