@Man
You can buy all the treasures that were left on the chests, but all the random treasures that you had to check pieces of the scenery for them, you cannot buy them back, and those also count towards the achievement.
I know i'm missing just one of two of those, but there are a total of 340 different random treasure places on the game, and i haven't got the time to check them all :P Maybe on a new playthrough with the DLC, i'll get it then
Current PC Build
CPU - i7 8700K 3.7 GHz (4.7 GHz turbo) 6 cores OC'd to 5.2 GHz with Watercooling (Hydro Series H110i) | MB - Gigabyte Z370 HD3P ATX | Gigabyte GTX 1080ti Gaming OC BLACK 11G (1657 MHz Boost Core / 11010 MHz Memory) | RAM - Corsair DIMM 32GB DDR4, 2400 MHz | PSU - Corsair CX650M (80+ Bronze) 650W | Audio - Asus Essence STX II 7.1 | Monitor - Samsung U28E590D 4K UHD, Freesync, 1 ms, 60 Hz, 28"
