I think the best advice about CD collecting that I can give is, buy spare empty jewel cases. That way you can basically buy used copies of CDs that are in shoddy condition for cheap, and just replace the damaged case and have a perfectly fine CD case, assuming the CD tray itself isn't broken and all the artwork is intact or in decent condition. 
(doesn't apply to Digipaks or Gatesfold/cardboard sleeves, obviously)