Sometimes you need to build your own house. There is a time to get a vision and run with it within your sphere of influence. People may criticize you for not including others or for joining others; listen nicely to the critics and then do the right thing.
Of course, there are other times to join together on things. I absolutely love the "Love Moose Jaw" project that churches in our city are joining forces on. What a great plan, what a great city, what a great demonstration of unity and God's love.