There may be something out there, but I don't know of anything. (Let me know if you find something!)

You could probably figure out by trial and error. Find out your voting power on https://steemd.com/@beriberi, then watch to see how much your vote is worth at different voting percentages. Make sure you are adding your vests to the calculation.

You know that your vests will give you a constant value per upvote when voting at 100%. The only thing that changes is your voting power, which lessens each time you vote.

Maybe something like this: [current # of vests] * [current voting power] * X (unknown amount a vest is worth) = $[dollar amount when upvoted]

I haven't tried this myself, so maybe the algorithm is more complex than that. But if a vest (steem power) holds a constant value, this would figure it out.