敝帚自珍
English Expression:
  1. n.  everyone values things of his own
  2. n.  value the broomstick simply because it is one's own
  3. n.  value one's own old broom - cherish something of little value simply because it is one's own
French Expression:
  1.   attacher du prix à ses propres affaires, mêmes les plus viles, Un balai usé est cher à son propriétaire