> I have been guilty of agonizing over spending $5 on a phone app while drinking a $5 cup of coffee.
Couple years ago I was working on a side project that touched upon what you said. The core idea was dead simple: you make a list of things you want to buy or do, along with the price. And, every time you feel like spending money on something that's either excessive or not really necessary (like a $5 coffee), you enter how much you saved. The app will then show, for each item in your wishlist, how close you're to it's price. Imagine a progress bar, inching toward the goal. Along with few other stats to encourage saving (but not to a crazy extent; we gotta live a little too).
I still have the codebase with some APIs ready. Wonder if I should just complete it and launch. I called it WIYS (What If You Saved)
Anyway, I think with software, a combination of necessity, choice & culture plays an crucial role in making people pay. For instance, I badly needed a window manager, so I'd have even paid $50 if there were no viable option. These kinda apps are tricky; if it's simple, the market will be flooded with options. If it's niche & the problem domain isn't a showstopper, people may not care. Also, we enjoy the benefits of so many open source s/w, and I think it creates a subconscious expectation to get everything for free - or at least to hunt for free stuff, even via piracy. While I still have traces of that mindset, these days I value my time more than money, especially if the cost isn't too much.