Well I've been running this forum for 2 months now and I have yet to break 500 members. I just need some ideas on how to kickstart this forum. Linky http://www.monetizationforums.com
run a contest and or hire a forum posters. that should do, but then running a forum still require lots of effort
500 members in two months is very good start IMO. I think you should keep doing what you been doing consistently.
i think you should decide first what do you want?? if you want to flip this in future buy poster but if you want to maintain it as unique and real ,attract organic members.
Did you get the Google SEO plugin? It'll really help your MyBB forum out quite a lot. You can then submit its dynamic sitemap to Google Webmaster Tools.