How much, in USD, would M$100 go for if it could be freely bought and sold?

I'm curious the approximate monetary value of mana, given it can be bought for a dollar and donated to charity at the same rate, but not cashed out. 

To resolve this, I will either devise an informal test to run, wait for one of you to do it for me, or resolve to the market probability at a random date and time in the week before the close date. Given that discretion, I will not be trading in this market.

Sep 22, 1:18pm: I've extended the close date by a week because I have my hands full working on a bot for the trading bot contest, so I want some extra time to figure out how to run an informal test on this. If this has been disruptive for anyone please let me know.