Business model I didn't expect

I never really would have thought there was a market for it, but apparently, power supply repair is a profitable business to get into. Now, I'm not talking about the forty dollar power supply in your desktop computer. I'm talking the power supplies used in lab equipment, high powered machinery, and industrial systems. These power supplies cost thousands, and it's cheaper to repair them than replace them. Hence why this business makes sense. It just wasn't anything I had ever thought about. pretty cool, though.