tanatos, we don't object to people on the forum arranging to work on paid programming projects outside of forum discussions, but this forum is almost exclusively about people coding stuff for free (though accepting donations after the fact if people want to support their work).
So while your intentions may be good, we discourage people from answering posts like this by offering to be hired for pay to do it. If and when someone decides they want to hire a programmer for a job, that's a different matter and I encourage you to reply to such people directly. Until then it would probably be better not to offer to work for hire when people post a request. Might seem strange compared to other programming sites, but that's just the way we do it here.
Back to the subject, I know their are existing inventory programs, both local and web-based, i just don't know the names of them. but surely some people here have some experience with them and it would be nice to hear from people who use such programs..