What are the best bolts to enchant in RuneScape

The best type of bolt to enchant would be enchanting onyx bolts from rune bolts. The cost of the tips cost about 8k each and it requires 87 mage. About the only way to get the tips without buying them would be killing tzhaar in the karajama volcano in the cave. The spell requires 1 cosmic rune 1 death rune and 20 fire runes. If you need any help just contact me. Im airborne389.