Well, i think that is not the most important question to ask.
U need to focus on what u will sell, what u think that people wants to buy..
Then name your price and see how that goes.
If your item is accepted by people and they love to buy it u will earn money. no matter if price is low or high.
And my opinion is that digital downloads and Ebooks goes very well on tripleclicks so maybe u can try with that.
