You need to make sure it's J-2534, Can bus, obd2 and can program OEM modules. A lot of the scanners sold on eBay, Ali express, Amazon, etc are not up to snuff for a real mechanic / business. Take a look at https://www.boschdiagnostics.com/products/mastertech-ii-j2534-vci
The pro stuff will break the bank though. If he want to just read/clear stored codes and view PIDs the MX+ will work good for that, but you might not be able to reprogram a BCM with the proper VIN etc. Although I have used a MX+ with ForScan fairly successfully on my own vehicle, just would not try it on someone else's.