The first time the Meike Pro Battery Grip for Sony a9 and Sony a7RIII was in stock it sold out very quickly from Amazon. Now that a few photographers are getting the grip in hand we are getting some feedback on the quality of this unit. Michael Schmidt seems impressed with the quality of the grip but does say it feels a little cheap compared to the OEM Sony Grip, but likes the feedback of the buttons better than the Sony Grip. The Meike Pro Battery Grip also adds remote and intervalometer features.
Meike MK A9 Pro Battery Grip: Amazon