Sorry for the delay. The monthly costs (which are actually closer ~$800-1000/month), are a small part. A bigger worry is if we take money from people, we really have some obligation to provide "reasonable" service. We've had relatively few system-administration incidents so far, but I'm concerned about something happening when we are on vacation or busy with other things.
Worst case scenario is Chrome changing how extensions work, which requires us to actually write code, or someone finding a serious security vulnerability.
As a conclusion: It really would take more like a total of $3000/month in fees to make it worth someone's time to deal with the paperwork, the administration, and to be willing to be on call. It seems unlikely we'll get there, but I'm investigating the possibility.
IOW, if this thing was to generate $500/month, would you keep bothering to operate it?
I happily pay $24/year for NewsBlur. I would happily pay/donate at that rate for Mitro.
And it sounds like _just_ the people in this thread would get you pretty close to $200/month given a model like that. I know more that would.
As other commenters said, the platform integration and password sharing are really, really great.