takinbo
There's going to be a problem of detecting counterfeit bills if you decide to take this route. As an alternative suggestion, how about using the same method of distribution some other cryptocurrencies have used in the past by taking a snapshot of a cryptocurrency at a certain future date and then having interested community members prove ownership of an address containing some cryptocurrency and using that to distribute the tokens? It wouldn't matter if someone buys cryptocurrency just for that purpose and then sells it afterwards.
The downside, is that you will be restricting distribution to only those who can gain access to cryptocurrency - which is also the same problem as taking a photo of dollar bills; the likelihood that those who will be using the platform will know/have access to cryptocurrency is high nevertheless.
SXSW Pokes: 50 stories about making a ruckus [pdf]
Multi-master MySQL replication using the poor man’s VPN
Facebook Groups in my opinion are a no-no even if all your group members are on Facebook and my reason for this is that it doesn't encourage active discussions. You always have to check with the group to know what's going on.
HTH