Speaking personally, it isn't something I would be willing to spend. It's within my budget, but I've never liked the thought of software as a service for something that doesn't feel like a service. No ill will to the developer, of course. I'll continue to use the original app.

The "service" would be continuous product improvements, technical support, hosting of the app and your hosting of your data. I think it's erroneous to seize on the "service" aspect of SaaS. In many cases you are effectively paying a monthly licensing fee for additional functionality within the app.