Skip the hypothetical question freshman approach; what do you want me to think about?
Rand, as I understand her, places a great deal of importance ('goodness') on doing what benefits materially number one (you). In the question about whether you think it's better to spend your hard-earned next thousand dollars on a new stereo (that we posit you want), or on a starving African kid is meant to see if you might (in your heart) obejct to that facet of Rand's morality. At the base of it, Christ's morality is based on love. Rand's is based on self. Highly different moral axioms lead to a highly different morality, which in turn lead to different ethical considerations in the quesiton above. But all that aside, what does your heart say?