It depends on how well you do. Here's what I would roughly break down the cost to be:
Primary app:
Mailing in transcripts:15$
Sending primary's to schools about 40$ per school
For me, I applied to about 35 schools primary.
~1300$
Secondary Apps:
About 75$ per secondary.
About 8$ per schools to send LOR's
I finished about 29 secondaries.
~2400$
Sunk Costs for interviews:
New suit/outfit: ~500$
extra shirt: ~50
~550$
Interviews themself
Hotel: ~50$ each night
Transportation ~50$
So for 11 interviews, that's about 1100$.
Away interviews:
Plane flights: about 200$ each (some of them were bunched together)
For 10 interviews, 2000$.
So my rough expenses: 7300$