Holy cow, thank you so much for this. Speaking of WTF reactions, I hope that won't be how this is perceived. Yours is a perfect example of both the insidiousness and the genius of Beeminder's exponential pledge schedule.

The fact that there's no doubt in your mind that you got more value out of Beeminder than the $130some dollars you paid is I hope evidence that it's more genius than insidiousness. :)

Yours is a textbook case of using Beeminder exactly as intended, to ride the pledge schedule up to the point where the amount of money at risk scares you into never actually paying it. For some people paying even the first $5 is sufficiently aversive. Others go all the way to $810, which has been, almost universally, sufficient to keep people toeing the line. (Ie, only one person has ever actually defaulted with $810 at stake.)

Some people (Katja Grace is an example) prefer to cap the amount at risk and are happy to pay a small fee occasionally. That has the danger of being more expensive in the long term as each particular derailment isn't a big deal and you can keep delusionally being like "ok, but this time for real!". Mostly, though, I think it depends on the severity of the akrasia for the specific thing you're beeminding.