I Agree with Wutangfinancial. He provides alot of good, accurate options:
About the MD...
You get your 4 year degree. Whatever that cost you.
You pay anywhere from 100K (State U) to 160K (private) just for tuition to medical school. Want free tuition do MD/PhD program for minimium of 7 years, more likely 8 years. You still have to eat, no job as you focus 24/7, say you live on 15K a year, so add 60K to your tuition number.
3 year (short, say one internal medicine) residency pays what 45K for 100 hours a week.
Your fellowship is anywhere from 2-5 years, you still get paid 45-55K for very long hours.
To me that is 10 to 14 years without really making any money post undergraduate. Then you cash in as Plastic Surgeon suggests, assuming you get into a good speciality. I also beleive you will work 50-70 hours week as specialist?
Those lucrative specialities are very competitive to get into, so you have to be talented and have done well throughout your MD grade wise. Most MDs are GPs, not specialists.
Again its a long road with alot of personal sacrifice.
Personally, I think a top tier MBA will provide greater lifetime earning potential, than MD. Aka the Snowball effect with earning money, as you are making say 200-250K for almost decade before those MDs are cashing in.
BTW, I have Science PhD. I don't recomend a PhD, unless you have a strong personality and really ready to suffer (high level of natural intelligence is a given). A PhD will train to solve problems both in out of your field, so you have alot of employment options all over 100K, most around 150-250K depending on field of study and employment place. FYI: A PhD is at least 5 years of study, most are about 6-7. The completion rate is about 30%.
I beleive MS in science or engineering field coupled with a second tier MBA is another good option as you can understand the field and manage at the same time. Many people understand the field and many people understand business, few can do both. MS & MBA grooms you for upper level manangement.