When you purchase items from a trader if you notice he has a resuply time on every item check that it will let you know when he will have that item instock again. it should be in the item description of the item.
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"That is not dead which can eternal lie / And with strange aeons even death may die."
H.P. Lovecraft
Quoting the Necronomicon, in "The Nameless City"
traders and augmentations 
Linear Mode
