You're not going to have multiple locations, good actors, good writing, good composition, quality cinematography, etc - unless you're incredibly talented and not counting how much your time is actually worth.
Films for a wide audience these days basically require - at a minimum - 6 specialists working for a month of shooting. Plus 5+ actors.
The absolute minimum that costs in labor - if you actually counted the value of your time - is ~$200k+.
A good script itself is worth well over $100k...
Realistically - it's almost impossible to make something with wide appeal for less than $2m in the US - or $1m internationally.
I would actually say, "almost nothing" in movie terms means, "human scale almost nothing" all the way to perhaps, "cost of a house". We all have phones, video editing software is free, there's plenty of distribution channels. If you want to make a movie for "almost nothing", you can do so.
Doesn't mean it's going to be good, or that anyone wants to see it.
Is this a peculiar concept? We all work OSS every day, right?
True, to the extent that any 90 minutes of smartphone footage uploaded to youtube is technically "a movie". In order to be "a movie" in the sense that Evil Dead or Primer are movies, I would say you need a bit more than that.
You can make a compelling story via flip book.