Before you can buy the secret trophies in Nier Automata, you have to spend quiet a bit of time with the game first. Three playthroughs worth of time to be exact. After Beating the Story Mode 3 times, you have to go to the Resistance Camp and look for the Resistance Woman who runs the secret trophy shop. You can get there quick if you choose chapter select.
Secret Trophy Shop in Nier Automata (How to buy Playstation Trophies)
Interact with the Resistance Woman and choose the option “Request unlocking you-know-what”. The Trophies you can buy there are very expensive and can cost you from 50.000G – 200.000G. So if you still have trophies that you didn’t unlock after your three playthroughs you can buy trophy 20-47 here.
YOUTUBE PLAYLIST for Nier Automata