A friend of mine - an old age pensioner - started up repairing/refurbishing commercial coffee machines in his garage. From then on this thing grew and grew. Now he has rented a hall in an industrial area to stock the spare parts he needs.
He cheaply buys defective coffee machines which dealers have replaced. He then either repairs and thoroughly cleans them, and flogs them via ebay. Or, if unrepairable disassembles them for parts which he either retains for other repairs or flogs these too after cleaning and checking. He only does the mechanical side. PCB are replaced, if defectve. He does not do component level repairs. On occasion I help him out doing component level pcb repairs. By nature, he has always been precise and meticulous in his work.