Missiles

+1 to hit OR damage: 5gp per missile
+2 to hit OR damage: 15gp per missile
+3 to hit OR damage: 30gp per missile

+1 to hit AND damage: 10gp per missile
+2 to hit AND damage: 30gp per missile
+3 to hit AND damage: 60gp per missile

Missiles can also be enchanted to explode or have special effects on impact, by modifying the tip or blade. These enchantments can't be combined with the bonuses to hit or damage, above. All special effects listed below are non-cumulative (won't combine with existing, similar effects, or multiples of the same effect). Hold and Freeze effects are subject to a saving throw. In the case of the latter, the Freeze does no extra damage. Talismans, potions, and spells won't affect the extra damage done by the Exploding type, although they will affect the damage from the missile, itself. Missiles of Guidance require no roll To Hit, and are incapable of critically missing or hitting. The prices and effects are listed below:

Missiles of Exploding: 40gp per missile [+d6 damage]
Missiles of Stunning: 15gp per missile [Hold, following round only]
Missiles of Paralysis: 50gp per missile [Freeze, following round only]
Missiles of Guidance: 40gp per missile [always hit]

Missiles are expended the moment they are used even if they do not hit the intended target. All missiles, including sling stones, can be enchanted in this way. Sling stones will carry no additional purchase price beyond the cost of magic working.