Since I don't do only residential cleaning, most of my equipment is relatively inexpensive. The most expensive piece of equipment I use is a 16' foot aluminum ladder that folds up and I can put in the back of my SUV.
I have been buying all in new and branded equipment's. I think in the future I will be making as many things as I can.. Not only do I get more experience I completely know how to maintain my equipment and repair without having to pay anyone else.
It depends on the item. New for things prone to breaking that are expensive because then you get a warranty and or money back. Used for small items that are fairly inexpensive, robust and easily replaced.