Able to give any context of what the SaaS product is, industries it targets, average monthly user revenue or even how long you've been running it?
The current pricing is about $10 per-seat/month. I experimented with a few pricing points, it's not optimal by any standards but it works so I left it alone. I wanted to make it as accessible as possible.
The product has been running since last November (2016). It was profitable within the first week and has been growing ever since.
I did no paid ads and no content marketing or anything like that. I basically cold emailed people I thought would be interested in it. It grew organically from there. Now there's a lot of blogs and people at conferences talking about it and I get traffic from all over.
As for how much maintenance/time I spend on it?
At this point I spend between 0-60 minutes a week on technical/code maintenance.
I spend 0-20 minutes a day (in the morning) on answering support/feedback questions and cold emailing potential customers.
It's not something I have to do every day, but it works well for me.
I tried their products out and decided I could do better myself.
I gave myself a fixed amount of time to get an MVP out in the wild.
In my opinion, you'll never "justify" the time. The only thing you can do is make your best guess, look at the evidence and just give it a shot.
If you're worried about time, sand box it. If you can't make it work, re-evaluate the project (move on or keep trying).