I plan on making a few small games with Construct 2 soon when I get a break from my day job (also in game development) so I've been looking at the income side of things as well.
When I first started using Construct 2 I took a freelance job for some experience. It was re-making simple educational Flash games in HTML5 with all the art/sound provided. It paid $150 per game and took about 10-12 hours for the first game, spread out over a week as I had to wait for feedback and do some tweaks. On that basis I take $12 to $15 an hour as the minimum pay rate I should expect from people looking to hire for Construct 2/HTML5 game development.
I've also seen a few sites (e.g. FGL) offer $200 for completed games rather than templates.
These are usually non-exclusive deals but can sometimes require implementing their API or something like that.
Often the games don't have to be terribly complex - e.g. an endless runner or simple puzzle game will do most of the time, as long as it's polished, bug-free and mobile friendly. These sorts of games can probably be whipped up in less than a week working part-time.
If you have a more complex game you should be able to get more for it, but it could require some negotiating and might not be much more than $600 or so.
Of course these complex games will take longer to develop too. So you need to weigh up development time against expected income.
Anyway, let's say you spend a week coming up with a simple game, another week submitting to game sites that pay. If you're lucky and 5+ game sites accept the game you could get $1000+ for those two weeks of work. Although, from what I hear, there is usually a bit of a delay between submitting and payment.
Plus you can still submit it to the app stores and sites that do ad revenue sharing (e.g. Kongregate) for added income.
It's probably not enough money to quit your day job if you have bills to pay (at least not until you have several games out), but it could be a good side income.
I think the trick is being able to churn out lots of fun little games and save the big dream project for when you're more experienced and have the income to support yourself. Having templates that you re-use yourself rather than sell should help.
You also need to know to which sites you should submit your game. A few people sell that information about publishers/sites but others share it on the forums.
I know this doesn't exactly answer your questions but I hope it's at least a little bit useful.