Here is a hint, Colin: any time a prospect says he's "run the numbers" on your pricing, you just received a strong signal that you need to simplify pricing. Purchasing decisions should be made in the limbic system.
Think about it: if you charged $5/mo and put an obscenely high cap on storage for the $5/mo account, then by your own math you'd be hugely improving your revenue, and at the same time you'd be charging half of this original poster's pain threshold number --- which is referring not to crazy encrypted backup solutions but to things like to-do lists!
At EnterAct, the ISP I ran tech-ops for, my old boss Mike Cloran came up with what he called the "5/30" pricing scheme, which we used to great effect to grab customers from other ISPs. Other ISPs were either metered (which scared the shit out subscribers) or flat-rate (which chased away light-users). The 5/30 plan was: $5/mo + $1/hour, capped at $30.
This is actually not a great deal and it is not particularly sophisticated (it is... wait for it... a capped metered plan). But it simplified the buying decision for people, addressed their perceived risks, and made EnterAct seem even more flexible than it already was.
Pricing is the hardest part of product marketing. There's a reason why established companies don't let just anyone do it. Your pricing scheme punts on it.