There is a curve to how many people will pay for a game based on price, which is different for the sort of game and who it appeals to.
In theory, if you could make an accurate function for how many sales you would make at each price point, with the other axis being how much money you actually take home, you could find the ideal price to make the most money.
But no one can predict the actual number of sales you will make with any particular game.
And a game designer may have other motives than making the most amount of money. If they’re a software engineer, and want to make the most money, they probably should try something other than games, whose profits are unpredictable, sometimes less than zero, and often not very much, with occasional exceptions.
I would suggest looking at similar games (if there are any) and looking at what they are priced at, and how that price changes over time. (Many “Triple-A” (code for, made on a multi-million-dollar development budget and also a huge advertising budged and their companies are connected with media so the games get people excited enough that they are willing to look for it and pay for it at full price) games cost $50–60 initially at retail, but then go on sale and discount.
There are so many games made, and so many of them are on sale or discount, that unless you have that marketing buzz going for you (in which case you probably have a Director of Marketing in your company instead of asking Fluther), that an Indie game in particular is competing both for attention/visibility and price with many games at lower prices.
On the other hand, there are many indie developers who make niche games that are so unique that they effectively have no competition and will be found and sold to fans, so they sometimes cost $30–60 and may nearly never lower their prices, which may particularly make sense if your game is niche enough that even at a lower price it’s not going to attract a lot of sales except from people who appreciate it and will pay more for it.