Write to YOUR Budget
If your goal is to write, direct, and produce your own films, then there’s no point in writing something you can’t afford to do or something that could require a hefty fundraising effort. This, obviously, depends on your skill-set, experience, and your ultimate ambition. If you are a VFX master, then you could and should definitely make a VFX-heavy film, but if you don’t know a thing about VFX, then what’s the point of writing a movie that depends on it?
Writing a movie that you can afford to make tomorrow will make your life a whole lot easier today and will increase the likelihood of your movie actually being made once the script is complete (even if you only have $300 in the bank).
The Grand Budapest Hotel had a budget of 25 million dollars. Is this a dream budget for many young directors looking to get their film made, yes. However, in Hollywood, this is considered a very strict budget. Take a look at how Wes Anderson and his crew worked around their own budget constraints and won an Oscar for their art director.