The mahr is an obligatory gift from the husband to the wife, commanded in the Quran: 'And give the women their bridal gifts graciously.' The Sunnah encourages that it be reasonable and not burdensome; the Prophet (peace be upon him) told a man who had nothing to seek even an iron ring, and ultimately married him to a woman for what he had memorised of the Quran, showing there is no fixed high minimum and that ease is praiseworthy. There is no upper limit in principle, but Islam discourages extravagance that obstructs marriage. The mahr belongs entirely to the wife — not her father or family — and may be paid immediately, deferred, or split between the two by agreement.
Informational, not a personal fatwa. Consult a qualified scholar for rulings on your situation.