What is a good business inventory / budgeting web app / client app?

My wife is a professional coffee taster and we are thinking about opening a coffee shop cafe without borrowing money (we already own machines, which is a major cost). The coffee quality in town is mediocre for a population of 135,000 and we think the standard should be higher.

Does anyone have any suggestions about good software that can handle inventory AND perhaps budgeting also? I prefer a web-app (but open to client apps) and I'm also a princess about UI/UX (chevasdesign.com) so if I am ever going to use it, I'm hoping that it's well designed.

Thanks!