$8000 is probably not the cost for interviewing. I interviewed at quite a few schools and did not spend that much just on the interviews. That figure seems a bit high to me. My guess is that it is the total cost of primary, secondary, and interviews combined.
For me, I spent rounghly $5000 for the whole cycle. Where did I get it? I worked and I saved up during undergraduate years.
And there is always plastic! 😀