In Iran when you ask a store owner the price of something, the answer is "It's free." Then you have to refuse a few times if it's free and then you can get the price. (Not my personal experience. But I heard the same thing from a few people.)
I have a good friend whose parents are from Persia/Iran. He told me about this culture after we knew each other for quite some time. Even though he has never lived there, he often still has a hard time not to do this, which has resulted in some funny (at least for his friends) or uncomfortable situations over time. Knowing this, many things I ascribed to his character alone suddenly made a bit more sense.