Code Self Study is completely free, but it's funded entirely out of my pocket. Since 2013, the project has only taken in about $100 in voluntary contributions out of thousands of dollars in expenses. If you would like to chip in a small amount to help offset the costs of organizing the community, please see below. Even small amounts (e.g., $5 to $25) to offset costs are greatly appreciated.
Expenses include meetup.com fees (hundreds of dollars in fees per year) and ongoing expenses of hosting the events.