If it's really not that expensive, couldn't you just self-host it? I think the developer is just trying to make a reasonable amount for providing a service for those who don't want to self-host.
[1] https://vikashbajaj.substack.com/p/the-slippery-slope-of-sel...
The developer should not only open source his/her work but also host it free for you?
I am merely comparing prices here.
Pricing an OS project isn't easy and we will introduce scaled prices per submission e.g. 500-2.000 -> 0,02$, 2.000-10.000 -> 0,01$ and > 10.000 -> 0,005$ or so.
We just didnt want to make it too complicated early on.