your costs will largely depend on how many schools you apply to and your general competitiveness.
1. applicants coming from the west coast (usually california) have to apply to 20-25 schools b/c their state schools are super competitive even with high numbers
2. applicants coming from the east coast and have medical schools that favor in-state residents can get away with fewer
3. the primary application with 25 schools set me back $900. I don't know what's the base amount or how much you pay for each additional school.
4. secondaries if you apply to many schools can set you back a lot with many costing over $100 each. These come after the schools have received your primary application and are usually sent automatically if you meet the GPA/MCAT cutoff (I think). However, just because you receive one, doesn't indicate at all your chances of getting an interview. Many times, after writing the check, people receive a rejection just a couple weeks later. Therefore, even if you are desperate to get in anywhere, keep in mind that adding every school will cost you a little financially. Of course, you could qualify for a fee waiver but it doesn't sound like you're that needy...
5. traveling to interviews is probably the most expensive component. You're looking at paying hundreds of dollars in terms of airfare and hotel stays. Having my mom travel with me for my first interview in total cost over $1,000. However, you can save a lot by staying with student hosts who will put you up for free.
It'll vary for everyone. Sometimes people get an interview from their dream school first early in the cycle and get accepted. Even if they applied to tons of other schools and got interviews, they can quit right then and there. For me, I had an interview as early as October. Of course, being me, I messed it up and got wait-listed, so I had to go to 3 more interviews before being accepted somewhere. However, if I had gotten accepted, I would've been done by September and saved myself 3 more trips. But yeah once you get that first acceptance, you can be a lot more picky...I canceled 3 interviews and am just waiting for my dream school.
Of course once you get accepted, none of it matters. When you get no acceptances, though, it can be really disheartening. Try to always stay optimistic no matter what!