Mahr is not a bride price. It is a woman's right and it signifies a husband's love and appreciation for his wife. According to the Shari'ah, the mahr should also be reasonable. There is no fixed amount of mahr in the Shari'ah. It should be given according to the financial status of the husband and according to the time and place.
Mehr can be anything, from a dupatta to a house etc.
Golden Question is:
What Haq Mehr did Usman put down on the Nikkahnama?