http://eng.yammer.com/ seems legit too
2 karma · joined July 26, 2010
Might lose some people, but if all 3500 stay, you only need each person to pay .015 per month. Of course this is just hypothetical. Maybe its $1/month.
Lastly, cash is king. Try to always get as much cash as you want, unless it is a really stable stock, i.e. Google/Apple.
In the end, get good counsel and it should be a market pricing sort of deal.