Chances are your initial expense will be zero. You most likely already own everything you could need. Almost everything available for purchase is unnecessary or completely ridiculous. Your friends and family won’t even know what to get you for Christmas over this new hobby.
Fill your everyday routine with daydreams and inspiration, imagine scenes and dialogues while your mind would otherwise go idle. Stuck in traffic? Turn up the music and imagine something. Bored doing chores? Picture yourself as one of your characters. Annoyed by strangers? Put them in your story and let a piano fall on their heads.
I truly think everybody should write. It’s such a delightful thing. Not to publish anything obviously - but because it’s fun, it’s easy and it’s completely free.