The history of American slavery is a history of slaves trying to escape the institution. We know some were successful, either by buying their own freedom or merely running away.
Were there ever any schemes for these former slaves to pool their money and free even more people?
I do know of one abolitionist John Breckinridge of Kentucky who encouraged other anti-slavery proponents to purchase slaves and give them their freedom. The idea was also discussed in several pamphlets and novels at the time, such as The Curse Entails. If this actually happened, the books I have do not give any examples or anecdotes.
A New History of Kentucky- Lowell Hayes Harrison