That makes me think of my balance sheet after 10 years of developing and paying Apple’s yearly 100 dollar developer fee.
I think I’m about a 1000 dollars under in total! 
I think it’s fair enough. Do we want Steam to be infested with cheap, crappy clones and shovelware like the app stores? It’s already heading that way, this at least provides some protection against spammers.
If you don’t think your game can make $100 why bother with Steam?
I have to say I concur: what’s 100 dollars per game? I would think that you would put in at least a couple of thousands of dollars into any project in (virtual) wages, so the 100 dollars shouldn’t matter that much.
Plus: you do get a whole distribution channel in return.
Just to clear things up.
That 100$ per game fee is recoupable. Valve will pay it back to you once your product has at reached at least $1000 USD adjusted gross revenue on Steam.
The only reason why that fee exists is to keep the worst of the worst and the laziest of the laziest games out of Steam, i.e. to help weed out effortless and “hey look at my first game”-type deals out of the store.
That’s understandable but I think there is way too much competition on Steam for casual games to reach a gross revenue of $1000 USD (at least not in a reasonable period of time).
BTW, what’s the average (user-accepted) pricing range for Corona-like indie casual games on Steam at the moment?
Well personally I’d rather casual games were kept away from Steam. That’s not what it’s for. If a game can’t make $1,000 then it isn’t good enough to be on Steam.
You can have a look at what other Corona devs have done and what they are asking on Steam: https://store.steampowered.com/curator/34260302-Made-with-Corona/
Your price should be based on what you consider the game to be worth and what you expect people to be willing to pay for it. Not what someone else is asking for theirs.