I believe that the best option is for the fans to buy the A's and then work to build a new stadium. The Green Bay Packers NFL football team is owned by fans who purchase stock in the organization. I know that a group in Los Angeles attempted to do this when the Dodgers were for sale. They ran into many difficulties, including stated opposition from Major League Baseball, Inc. and never did get off the ground. The website for Own the Dodgers was taken down, but they currently have a Facebook page at:
It would take a lot of organizational effort and perhaps some local civic groups would get involved. I hope that this becomes an active thread.