Zenons (if fitted properly) will cost a lot, complete pair of lights inc bulbs go for about £450/£500, then you will need the plug adaptors £38 then you will need level sensors (i paid £60 for the sensors and a CCM) then you can either make your own looms for the sensors (say £15) or buy a kufatec loom £80 then you will need the height control module £40ish on ebay, and then last of all headlight washer system
Prob about £800 to fit them so they will pass an MOT, the MOT laws changed on 1 april, if you have xenon headlights you must have level senors and headlight washers fitted