Homestead Arcana

Abraham will visit your homestead every morning (beside your mail box). He'll sell 3-4 items each day which usually adds up to around 200 Silver (early on in the game). I managed to get this on Abraham's first visit by doing a Save before speaking to him, selling all my inventory and buying everything he had. Once the achievement pops, Exit to main menu and load back into the game before the 5 minute Auto save kicks in. You'll have your full inventory again with the achievement.