I had a deal with him for $3. While sending payment, I just made a joke (my net was slow, so as to pass the time). The joke was 'I sent you money !'. I told just this much and he refunded the money. After my lot request, he agreed to sell for $4 which was the price he told at start.
So, I think he is very clever and serious person.
Thanks to him for I learnt never to joke with unknown people with whom we are dealing.