Before we kick this countdown off, let's run down some of the rules.
1. The transfer must have taken place between two La Liga sides.
2. The player must have been signed as a first-team player, not picked up as a teenager to bring through the youth setup.
3. The player must have demonstrated longevity at the club he signed for—quick-hits don't cut it here.
4. The transfer fee should represent value for money...