On the topic of belt/promotion fees, color belt fees are minimal ($25-$30) and mostly cover the price of the belt and the instructor's time. These are held at the local school. The belts are white, orange (1 stripe), green (2 stripes), red (2 stripes), midnight blue (black, 2 or 3 stripes), master/kodanja (midnight blue with red stripe). The other requirement is to be up to date on your national membership fees ($80/yr). Black belt tests are significantly more expensive, starting at $450. This is mostly because we test by region, our region is the rocky mountain states from Canada to Mexico. It lasts a weekend and it requires us to bring instructors from other regions to hold seminars and be on the test panel. We try to at least pay for their hotel and help with airfare etc plus we need to pay for the hotel conference space, etc... We hold these tests every six months. We encourage all Dan ranks, whether testing or not, to attend the event and seminars (about $100 if signed up for seminars). It's a good fellowship/networking/training experience. The kodanja test is yearly and at a national (or international if you choose) level. I don't know the cost of this but it's probably comparable in terms of fees. This test is eight days long and "visitors" are also welcome to train along with the candidates and assembled panel.
As an aside, if I ever started my own school I would charge more for color belt testing ($25+ as suggested donation) and either pool it to pay the fees for my students testing for Dan ranks or use it as a scholarship fund for yearly national organization fees. Or some combination of this. I don't own a studio so I don't know but I suspect that cost of belts in bulk isn't too much and can probably be rolled into operation costs without too much effect on the bottom line (again, I'm not an owner so I don't know).