Tons of good options in the used enterprise market. 3-5 years old, usually some paths for basic upgrades, as well as a flood of part availability from all the other similar systems being off boarded that were broken and not resellable. Laptops can be a bit roughed up, but full sized and sff desktops are usually in great condition.

This is the big reason. I keep the boxes to make future moves easy, learned the lesson the hard way.

Other good reasons are the box keeps all the accessories in one place while saying what they are for (psu boxes, looking at you) or the box is great at storing that type of item, like the box my NAS drives came in, perfect foam insert for other drives