HS applications have first been developed as proprietary shareware, denying them a developer community legacy. This in turn influenced their development, which made me end up, as I open sourced them, with a development environment that wasn't very friendly to new developers.
This is a situation that, since the beginning of 2014, I am determined to correct, notably by putting a lot of effort in the documentation. I've been enhancing the developer documentation (which is now directly included in the user documentation) for dupeGuru and moneyGuru a lot lately and, even if there's still a lot of work to do, it's beginning to look good.
The very important thing to remember is that if the documentation is not adequate and that it's blocking you from contributing or figure out if you'd like to contribute, please, contact me. I am more than willing to put the effort into fixing such problems.
About money contributions. I don't accept them anymore. I really, really hate doing the extra paperwork when it's tax time. Besides, I don't even like money.
If you have the time and the motivation, you could go read the various articles I wrote about how HS apps came to being free-of-charge open source apps, but it's a rather long read. The important thing to know here is this: All the time I've spent developing HS applications has been paid for, so you don't need to feel sorry for me or anything.
If you're feeling like contributing money for this software nonetheless, I encourage you to contribute 20$ to a non-profit organization of your choice. If you're not sure which, I would strongly recommend the Electronic Frontier Foundation which is pretty good at defending our digitals rights and fighting the bad guys.