He is browsing for potential acquisitions in magazines.
This sentence looks odd. Should I replace "in" by "from", or should the sentence's structure be changed entirely?
It depends upon what you're trying to say. If your friend is in acquisitions and is considering companies that publish magazines, that's different from if he's browsing magazines for potential acquisitions. If the latter is intended, I say go for user606723's suggestion. If the former is intended, I'd recommend expanding your sentence to refer to "magazine companies". I honestly assumed the latter with no ambiguity of meaning in my head until I forced myself to think of other ways to interpret it.