Insofar as Beeminder is a tool to make hard-and-fast commitments (which is what it was built to do), you really, really don’t want to start messing with this sort of thing.
For instance, you lose the ability to do this, and the urgency that goes with it: intrinsically, having the flexibility to do it by the end of the day means that in the middle of the day it’s not urgent.
If you’ve pledged $205 that you’ll do this list of 41 things, and you both expect to not, in fact, do half of those things, and at the same time you don’t want (even in the long-term, non-akratic sense of “want”) to pay $100… well, then it certainly seems like you pledged the wrong thing!
Put it this way: if you expect that in some days you won’t do half the things, then you (upfront) have two choices. Either you decide that on such days you’ll pay $100, or you decide that you don’t want to do that.
The second option is a perfectly fine choice! $100 is a lot of money. You don’t need to decide to do things you don’t want to do. But you should be honest about it up front. You shouldn’t say “Oh yes, on such days I’ll pay $100”, if up front you don’t intend to.
So then why did you say exactly that to Beeminder? I have a good guess, that it’s because Beeminder doesn’t let you pledge less than $5 per goal (except $0), even if you are a Beemium user.
Imagine if you had pledged $1 per goal. (Or if even paying $20 is too much, imagine if you pledged $0.50 per goal.) Would that change how you viewed things?
(All this is really also a response to what you wrote in the other thread, and might be more on topic there. But here is a more concrete tie-in. Probably it would have been better if these were both combined into one forum thread.)