Warranties on refurbished items vary from seller to seller, so it's hard to give a single hard-and-fast answer to this question, even knowing what the item in question is. If there's a short-term warranty on the headphones, then it's a more-than-fair price; if the headphones are functional and working, it's unlikely that the person who briefly used them did anything that would shorten its lifespan. If it's a refurbished item but no returns allowed, then I'm more on the fence about the whole thing.