We wanna go shopping with Mary J. Blige! The singer was at the Diane von Furstenberg store in New York last week when she overheard a girl having some trouble at the register. "The girl had a dress on hold that she loved, and the bill was $900," a spywitness tells Page Six. "She thought it was only $500, and she couldn't afford it." So the singer spoke to the saleswoman and said, "Go get the girl. I want to pay for the balance on the dress." The customer declined her offer to pay for the dress until Mary J. said, "I know what it's like to want something and not be able to have it. I insist." And when the customer offered to send a check for the balance, she said, "Just enjoy it. I'm blessed, so let me do this." How sweet is she! That story makes us want to go out and buy 10 Mary J. Blige albums!