I hate pricing my e-books too low for their value. I’ve put my first one at $4.99 because that’s what I believe it’s worth. If people are interested, I don’t believe they’re significantly less likely to pay $4.99 than they are $2.99.
However, I also have some short stories (c. 8-10,000 words) up for 99 cents. They sell more easily, of course. If you’re worried about people being unwilling to test the waters with unknown authors, you could write some shorts in the same genre as your novel–or even with the same characters–and offer them for cheap. Then if people like them they can step it up to the full-length work.