I hate to be the cynic (lies), but there's no such thing as a "passive income". The moment you put your service online you'll have active maintenance and support, even if you don't charge for it.
The other problem is that if you solve a problem well, it's actually extremely hard to avoid the business scaling. Once the revenue goes past 1k/month, it'll carry on going, and few people can bring themselves to remove purchase links.
I know that's essentially what you're asking, but my answer would be no, it's unlikely that you can find a model that fits exactly the criteria you have.
I notice many people posting ideas, rather than low-maintenance ideas.
Totally agree - in my experience, passive income is anything but passive. It's more involved than most 'real jobs' I've worked.
Have you tried negotiating tax forms, outsourcing (ha) customer support, maintaining a partially hacked-together codebase, or even having legal documents written that cost an entire month's salary?
There are a great many unsexy things that need doing when you run your own business, which regular jobs shield you from (my next 8 weeks' task list is currently averaging 300 items) - that's the trade-off. And then there's the 12-hour days you'll put in for months, while setting it up...
Sell an information product. They don't really have to have either maintainance or support.
I have an ebook out there that I haven't touched for about 2 years. I check the email address associated with it about once every three months. It's still selling.
However, you are absolutely right - maintainance and support can turn a passive product into something Not Passive At All. It's something to watch out for very carefully if you genuinely want passive income.
Also if you are picking an area with competition it is very hard to stand still and collect your $1000/ month, either your pushing on to something bigger or your $1000/ month starts declining pretty fast.
The other problem is that if you solve a problem well, it's actually extremely hard to avoid the business scaling. Once the revenue goes past 1k/month, it'll carry on going, and few people can bring themselves to remove purchase links.
I know that's essentially what you're asking, but my answer would be no, it's unlikely that you can find a model that fits exactly the criteria you have.
I notice many people posting ideas, rather than low-maintenance ideas.