I would reconsider your rejection of a web app.
Your LAMP stack won't be too bad since I assume that your database is already in place or at least it's no different whether you use curses or web. If your app is simple enough, all you have to do is add a vanilla Apache instance and off you go. The CGI part is probably easier than doing curses and you can get a lot more free help with CGI.
Second, this sounds like you'll not have a huge userbase. Even if it's large, I'll bet it's well-defined numerically at least. I mean you probably know how many people are gonna use it, so you can evaluate pretty easily how much power you need for your web server and growth will be controlled since someone can presumably tell you "Hey we hired 10 more data entry folks" and you can add servers. In other words, the scaling headaches of typical web apps are probably not in your problem space.
Third, think of your career!