Honestly it's usually cheaper to just replace the control arm. They are fairly cheap online, and the effort to bust out the rivets can often not be worth it, and a mechanic might take an hour or two to do all that, so it ends up costing more anyway. Also, the control arm will have new bushings, which often wear out with the ball joint.
On mine, they were so rusted the mechanic said busting the rivets would probably mess up the arm itself...