The dowry is defined in the legal text books as: "the wealth the wife deserves upon her husband as a result of the contract of marriage on the consummation."
There is no specific minimum or maximum. The customs of the community play a great part in deciding the agreed amount to be given as dower. In the past, families would ask of a dower which reflects the social status of them. After the spread of education and the maturity of age of both husband and wife, families began to relax this custom, taking into consideration that young people who start work after graduation do not have much money to offer for the girls they have going to marry. Families have come to the realisation that dower is a symbolic gesture. It is good to start building their family life without incurring a debt which may ruin their happiness and future prospects. If both husband and wife are working, the families may prefer that the young couple build their life from scratch together, rather than burdening them with hefty dower which they cannot afford.
It is not Islamic to ask the woman to give dower to the husband. This is not a noble thing to ask a woman. The Islamic requirement is not because the man is going to buy the woman, it is to express his love, care and the dignity of the woman. Whatever expresses these sentiments, great or small, is considered to be an acceptable dowry, simply because it expresses these feelings.