It doesnt make any sense, What is the point, yo say you can buy 4, but you are endigg up paying way more for 4, maybe not in money, but in time, effort and risk or mutiple things.
Lets say you go the 4 pumps route, yo still spend the same amount of money, but one fails, your home, no big deal, because you happened to be looking at the pump, you change it, because you happened to have all the time in the world, just until the moment it breaks and you are not home and you dont have the time, thats when problems happen. If it happens again and you are on vacation, or simply not home, what happens then?
Whats the point of paying the same amount of money for something thats going to cost you more, your peace of mind, your time and effort, and even maybe your whole investment?