What about the easiest way?

1. Add a low price for the first days, ie: 0,99.

2. Then tell a bunch of your backers that you want to give them 1$ via paypal or similar.

3. As you get responses and the application has been bought jump to the next bunch of packers.

4. Repeat.

5. When finish, raise the price you consider fair.

It will cost you around 30 cents * N. of backers and you will get a bit of traction from some early users thanks to the low price.