I've compiled a list of businesses that are sharing their expenses publicly, adding this one as well: https://github.com/jmstfv/open-expenses

On the stack itself: it might seem overpriced (or even overengineered), but if that's what they're comfortable with, so be it. Getting your product out there faster and being more agile (no pun intended) is worth much more than saving here and there - you can always optimize later (which is a place most businesses won't ever reach, unfortunately).