You have to look at the total cost of all four years though. For instance, Columbia's budget never gets too far above $59k/yr like you mentioned, but let's add it all up (
http://cpmcnet.columbia.edu/student/finaid/PDF/mdbgt0506.pdf):
Columbia
1st year: $57,560
2nd year: $59,436
3rd year: $63,574
4th year: $59,246
Total: $240K
Northwestern
1st year: $61,234
2nd year: $77,608
3rd year: $75,388
4th year: $32,853
Total: $247K
The point? 1) Private medical schools are all expensive, 2) these budgets are a big joke because no one ever spends what they propose and the only sure bottom line cost is tuition, and 3) I have too much time on my hands (which says a lot of positive things about the Northwestern curriculum).
BTW you also have to consider bang for your buck versus many places as far as lifestlye since, for instance, the equivalent of my apartment in NYC (amenities, poshness of location, sq. ft., what floor you're on, etc.) would probably run into the mid-$2000/month range, and wouldn't even be available in places like the Boston or the Bay Area since they don't even build buildings that tall there.