http://minecraft.gamepedia.com/Trading

• 5 - 19 emeralds for Lvl I
  
• 8 - 32 for Lvl II
  
• 11 - 45 for Lvl III
  
• 14 - 58 for Lvl IV
  
• 17 - 71 for Lvl V
  

• iron/diamond tools
  
  • Unbreaking III/Efficiancy III/Silktouch I or Fortune II
    
  • http://www.minecraftenchantmentcalculator.com/#11617

• iron/diamond sword
  
  • Sharpness III/Looting II/Knockback I/Fire Aspect I
    
  • http://www.minecraftenchantmentcalculator.com/#11817