Hey There,
Tnx for your response. We can certainly post it on our Facebook group and website – still its a small coverage.
We could also spend some of our own money to promote it specific to your area on Facebook – that also can help and is not too expensive.
Are there any more strategies we can use to make it grow sustain-ably?
I would suggest to investigate and propose some here:
http://www.meetup.com/help/keyword/promote/