Matthies explained the investment idea very well. It's either a good investment because you know that, God willing, you will earn market when you graduate regardless of your class rank, or because your debt is minimal and you can live happily on an entry-level salary (e.g., 50k).
If it's the former, I would say that a top ten school is your goal. I wouldn't go lower than Duke and Cornell, but it's possible that schools beneath them fare just as well. (My school should be apparent from the moniker.)