*Note that this Trophy can be bought in the resistance camp after playthrough 3*
Solution not using the shop found below
As part of the main story you will receive a scanner module for your pod. It allows you to find buried items by using the scanner kinda like a game of hot & cold. The closer you are to a buried item the faster the scanner will beep (You have to keep the button held to keep the scanner active)
Personally, I got all of my buried items, especially as there is a side quest in the desert at one point of the game that requires you to find a few buried items in order to complete the quest