I think he's really kidding! really unbelievable price. By hearing that price, the red alarm bells in my mind. There is a big chances fraud is there. Olx itself tells some precautionary methods, which should be followed by one who wants to go ahead.
Reasons for that price...
May be they are demo pieces, selling repacking them as sealed ones which many newbies wouldn't notice .
May be they're getting imported illegally without intn'l warranty, etc, having some sellers warranty (which is anyway not useful in case of fault arises).
If possible call them and go further safely like you would purchase, you can understand by their words whether they are professional or some frauds, see the box packed set physically, get the serial no. of the tv, confirm with Samsung India CC and its warranty. Don't let them for door delivery, and finally pay only if everything satisfies you (I dont think you want to do it!!!). If u or they did this, share ur exp here for the sake of awareness among us.