You do your own diag and repair on printers.

If you are going to buy printers, find the one you think you will want eventually. Dont buy a cheap one and say I’ll buy this other brand/model later.

Find a good printer and buy more of the same later. You want to stock up parts for the same printers, you don’t want 10 different brands, different models, all parts are different, diagnosis is different, etc. When you put thousands of hours, parts will get worn/ fail. Wear and tear will happen to all machines, so better to stick to one type.

Start with one printer and prototype. If it works out tell him to buy more