Costs nothing from a friendly cleric.
Typical Friendly Cleric running around with a Fighter: *Cleric casts:* Mage Armor, Divine Shield, Greater Magic Weapon, Stone Skin, Every Buff, Divine Favor, Dark Fire, Protection from Elelments of all Kind, Aid, Prayer, Prot Evil, Neg energy protection, Freedom of movement, spell resistance, death ward, battle aura, regeneration, aura vs alignment, and a few other spells, on himself. *Looks at the fighter* Oh, sorry dude. *casts Aid*. Yoiks!......And Away!
~Rex