There are a lot of open questions with this before any advise makes sense. It REALLY depends on your friends requirements (budget is important too, so that is the one thing we know).
What do they want the cameras for? How many? What do they need/want to see? How much detail?
My guess is that based upon budget they will deal with what they can afford. But also, how much time do they want to record? Maybe they want to invest in a system with more options on the DVR side?
If they only have 3 or 4 key areas - then you could likely get much better cameras than the 8-16 kits you are referring to. Or maybe they are dealing with a nuisance neighbor and really want to invest in 1 HD IP camera so they can read a license plate and provide the police with some real data. So, type/quality of cameras - will dictate cabling, DVR/NVR format etc.
Or just a couple Drop Cams so they can see who is at the front door or back door from an app - no DVR.