Getting some heavy vibes of Strugatsky brothers' Roadside Picnic here (a book that would come to heavily inspire the STALKER game series), right down to picking up impossible artifacts and selling them for profit. Not sure why this is tagged isekai though, as there's nothing even remotely isekai-ish in the story.
edit - Well I should have looked at the title more closely. It makes perfectly clear what the inspiration was.