Do you think is practical to build an internal invoice system that takes care of the whole VATMESS? How long do you think it'd take a single developer to do it?

Do you think is practical to build an internal invoice system that takes care of the whole VATMESS? How long do you think it'd take a single developer to do it? I know that there are many different services like the ones in this thread, but as a single developer, on a bootstrapping project they'd still be out of budget