I agree with Servant, charge for the game what you think it's realistically worth. There is a prevailing idea that game prices must race to the bottom, therefore to $0. I disagree, there is a cost to "manufacture" (aka develop) a game and as long as the game is worth it, people will pay for it.
Games like Dear Esther, Gone Home, and Antichamber now launch for between $15 and $25 - though they have frequent sales as well. These higher starting prices, coupled with sales at much lower prices, is actually a price-point that is economically viable for games (in my opinion).
+1 This is a great point.