The first part of your question is easy to answer, a replacement Trackball assembly is under $10 at the CrackBerry Store.
The volume switch is a little tougher, it is physically connected to the logic board and requires specialized equipment to remove and replace. Not a DIY job.
The side buttons can be found here, also they have new side rails that include them, if you feel it is just the button and nothing to do with the Logic Board.
I would replace the trackball on your own but leave the volume to a technician .. If you don't have the money you still can't up the volume for ringers or your music in the phone itself
Posted from my CrackBerry at wapforums.crackberry.com
