Infinite very rare (purple) mods
Go to the Scrapper site located west of the campfire during the “A Seeker At The Gates” main quest. Once you have access to the “A Seeker At The Gates” main quest (earliest you can reach this area), travel northwest to reach the campfire, then proceed west (follow the river) to reach the Scrapper site. This is the same area where Aloy saved the man that fell when she was young. While at the Scrapper site, hide and kill the Scrappers while remaining stealthy. Loot the Scrappers to get two very rare mods (+42-43% Corruption Coil and +38% Handling Coil, +37% Damage Coil, or +35% Shock Coil) that can be used to upgrade your weapons and armor. You can also sell these mods to get money to buy better weapons. These mods are useful early in the game, allowing Aloy to become very powerful in the early game. Fast travel or run back to the campfire. Use the campfire to save, then quit the game. Continue the game after quitting, and return to the Scrapper site. Kill the Scrappers to get the very rare mods again. Repeat this process as many times as desired. This same exploit can also be used in other areas of the game where enemies always drop very rare items.
Scrapper Site Map: