Hi Farrah,
I too was really worried about money before I applied, but I there's an excellent strategy you can use to keep the costs down. Try to apply early to rolling admissions schools that are high on your list. This way if you get in early (read: Oct-Nov), then you can avoid some secondaries and interview costs at schools you're less interested in.
Using this strategy, I applied to 16 schools on the AMCAS, completed 12 secondaries, and interviewed at 7 schools. The total cost was $2,500.
In addition, if you're booking an expensive cross-country flight, try to coordinate with a couple schools in the area to have your interviews on the same week/weekend. Always stay with a student host to eliminate pricey hotel costs and get discounted plane tickets online from Expedia, etc.
Best of luck to you!
sv
P.S. you might want to change the poll categories to <$1,000, $1,000-2,500, $2,500-4,000, $4,000-$5,500, and $5,500+ to give you a better idea of what to expect.