Bar Management

I have a requirements for a small bar/canteen run by a charity in NZ The key points are: * The Bar/canteen is used by two different charities, ideally need to run two pricelists. Most items differ by $0.5 except one which is $1 different. * No cash is taken during any transaction * Bar tabs are usually open for a month, this doesn't have to be the case but it can be a reference. It might be best to close each drink purchase as it is made for better reporting * Ability to keep track of stock and when it is running low, ideally with images of stock. Email the bar manager when the stock is low * select user purchasing and what they are purchasing and add it to their bar tab, tracking their purchased items and the cost * users able to see what they have purchased and how much their bar tab is * notification via email when their bar tab is getting close ot the $40 limit * only about15 different drinks and peanuts and chippies, so this is not a large setup, for about regular 18 actual users * ability to set up a user where all drinks assigned can be set with 100% discount. where the manager wants to discount all drinks but this should have authorisation really. * some kind of report for the accountant to show drinks consumed and money spent. I considered getting an android app written but i think this will be expensive as the application is not the important part, it is the back end system which will be web based. There are COTS apps for this already, but they don't handle the bar tab component well as tickets or tables need to be used, and one example is Loyverse which covers most of what i want, but doesn't handle the bar tabs in a quick manner. The image i have attached shows a rough flow, from selecting the organisation, creating the event, display of users, display of items, then closing the event. The other sections show the inventory and user creation options. I can draw this framework up if required in a clearer manner. I am initially want to get an idea of cost to complete before i can progress this as it is for a charity and any spend would have to be cleared first.