One thing to remember about pricing, its nothing to do with your costs. Charge based on the value to provide and the customers ability to pay. I agree about removing the free plan, i'd have 3 plans, 1 at $35 for the mom and pops, one at $99 for your main bread and butter and then one at $499 a month for enterprise, where you offer premium phone support, training, and other general perks that enterprises love.

Give a 30 day free trial of the $99 plan and then make them pay after that. As others have said, people on the free plan will cause you 90% of your support problems and you're making no money from them.

This app looks like it will generate a lot of value and save a lot of time for businesses. So look at it from that perspective, not based on what your costs are. If you're saving just 5 hours a month in a mom and pop business, i'd argue that $35 a month is easily worth it to them.