Surrogacy, Good or Bad Idea!?...Please Help!!!?

I'll start out by saying I already have a son. I'm also married. I'm in college as a Pre-Med major so I'm digging my self and my family into debt. I know that after I complete Med school, plus a few years for internships, I'll have a pretty good job and be able to pay stuff off (after years and years of saving) Ok so now to the point. I've been thinking about being a Surrogate for a family that can not conceive. I've always been one to want to help others, and think this could be a good way to earn some money and help a whole family! What are ever ones thoughts? Please Help.