More than half for me, back in 1994 I wrote a 360° 2D platform scroller in assembler and figuring out how to do tiling, scrolling, clipping, rain effects, parallax, collision detection, audio and video on my own from scratch in a single thread of execution was more fulfilling than designing and creating levels and is the reason I never finished it. The only algorithm I looked up was bresenhams for drawing lines.
Of course I can see why many people would want to avoid that and focus on other aspects. These days I have less time so I leverage libraries and try to finish projects ;)
I released an asynchronous JS pathfinder that handles path priorities and works on much, much larger grid a few years ago: http://lumakey.net/labs/ariane/
Seriously man what are you thinking? Have you ever made your own project? There is NOTHING wrong with trying to make a business out of something you created and I'm pretty ticked off that there are people out there writing stuff like this.
Why the outrage? If they're promising support, charging makes sense and in any case: their code, their license. It's not like anyone is required to buy it and it'd cost you way more than $60 to duplicate it.
Well considering it is probably a copy of someone elses who spent weeks figuring out the math required to do path finding while working on MSDOS or something. I kind of agree.
But then you see it also includes developer support and such so it all makes sense.
However this does lead to an interesting concern, what's the difference? I don't seem to see anywhere were it says you can't use the free version for commercial? Or what you get for free and what costs $60?
https://github.com/qiao/PathFinding.js
Demo page here: http://qiao.github.io/PathFinding.js/visual/