By the way, I signed up for Tarsnap and am using it "in anger" for Appointment Reminder. My predicted bill for this month is something on the order of 60 cents. It is, literally, the smallest business oriented bill I have ever forced my accountant to look at, and would fall below the noise floor but for the fact that I want paper records of me having paid for a professional backup service in case I ever have to prove this for my insurance agency. (I have professional liability insurance and data loss/data breach insurance for Appointment Reminder, chiefly because I have hospitals as clients and they want to know that if I screw up there will be deep pockets in the neighborhood to sue to settle up with. The insurance company is basically renting their deep pockets out on a "We are willing to bet that you won't screw up" basis, but to protect their interests, they have a 15 point checklist for various things Serious Businesses do regarding data security and if it turns out that I'm not a Serious Business than my Serious Business Insurance Policy will not actually cover me.)
I would, and this is my honest and true opinion as a customer rather than as someone who has nagged you for years to raise your prices, prefer to pay $100 per month for no reason other than to avoid having my insurance company think that I am a stupid kid playing at being a real business by entrusting core parts of my infrastructure to a service which costs me sub-coffee money. In the event of me having an insured loss (which, n.b., I hope to never have and to just set fire to the $10 a day I pay for insurance), I really don't want to have that conversation. Please make me not have to have that conversation. I can pay.