What is a car dealer most scared of?

i recently paid $ 300 advance payment for a car and got a receipt that does not say 'Non refundable'. Later i decided not to purchase the car because i didn’t really like the color (my fault!). i verbally told this to the car dealer in one day . (not much of a delay i think) the car dealer said he'll refund the money after the car is sold. (verbally). now the car is sold almost 1 week. i went and asked for my refund and the car dealer very rudely said he'll give me only $ 200. he just said he has 'lost' because i didn’t buy the car but refused to elaborate on how he lost. he is also very reluctant to pay back anything now. i asked him again and now he is avoiding me. he says vaguely something like 'the cheques have to be cleared ' and is avoiding me/ignoring me/doesn’t answer my calls. i am mad with him because he gave me hope and now is trying not to refund the money. i think he is a cheater. this is an individual company with no big company policy. what is the best way for me to teach this guy a lesson for not keeping HIS word? in other words how do i scare him? shall i report him to the customs? he is a Japanese car importer.