Just did a cheap install on 2013 Passat TDI SE... The 35W (4300k) kit was $25 on eBay, and the MK6 type bulb holders (H7) were $3.50 shipped again on eBay. For under $30, the install took me an hour but I really wanted to do it right and clean. The rubber sealers on the back of the headlights don't need to be drilled, don't be silly, a half an inch poke/slice with a kitchen knife made openings that are good enough to get the wiring through. Double-sided tape to hold the ballast to the headlight plastic assembly (there is tons of space), and t-type splicing connectors (4 of them for less than a buck) to clip to the wires. The wire harness is visible and the brown wire is negative on both sides, and the yellow wire is positive (passenger side had a blue stripe on it, drivers side had a black stripe). Everything was pretty simple, and without any cutting, soldering or breaking it should be reverseable within minutes if desired. Turned them on, and looks great. Cutoff stayed the same, a lot more light output, and perfect white light, not blue crap or anything. It's hard to know it's an aftermarket mod looking at the car with them on, looks like the car should've come with these to begin with. Super happy, I hope they last awhile!
They came with 2 year warranty by the way, so I know that I will have 2 years of HID for $30 in the worse case scenario. Replacement of both ballast or bulbs should take seconds so I'm not worried about quality at this point.
Very happy I must say... The USP kit looks good as well, but I just don't see why pay 3 times the price for the same thing.