If a poor person, earning $30,000 to support a family, gives $3,000 to Tzedaka, thus making a major dent in what he can afford for his family, and a rich person who is single and earning $300,000 gives $30,000 to Tzedaka, and still has more extra money than he needs, does the poor person earn more schar? Both gave it with the same joy.
L’fum tza’ara agra.
http://www.theyeshivaworld.com/coffeeroom/topic/poor-baal-tzedaka-vs-rich-baal-tzedaka