So to craft a javelin of lightning, you need to be able to cast lightning bolt. My druid can't do this, but if he bought a wand of lightning bolt, could he use this to meet the requirements?
On Magic Item Creation says
Note that all items have prerequisites in their descriptions. These prerequisites must be met for the item to be created. Most of the time, they take the form of spells that must be known by the item’s creator (although access through another magic item or spellcaster is allowed).
Thus a creator that wants to create a javelin of lighting could meet that item's lightning bolt prerequisite by expending charges from a wand of lightning bolt instead of, for example, by expending lightning bolt spells from his daily allotment of spells.
(Because of a javelin of lightning's market price of between 1,001 and 2,000 gp, each javelin typically takes 2 days to create and requires a lightning bolt spell each day of its creation. This makes it expensive to meet a javelin of lighting's prerequisites using a wand of lightning bolt—each charge of a typical wand of that 3rd-level spell at caster level 5 has a market price of 225 gp! Also, a typical druid doesn't have the spell lightning bolt on his spell list so the typical druid will need to make Use Magic Device skill checks—or have some other way—to activate that wand of lightning bolt.)
Meeting this lightning bolt prerequisite for a magic weapon, though, is often considered unnecessary. See, on Magic Item Creation also says
At the end of this process, the spellcaster must make a single skill check (usually Spellcraft, but sometimes another skill) to finish the item. If an item type has multiple possible skills, you choose which skill to make the check with. The DC to create a magic item is 5 + the caster level for the item.
Because the typical minimum caster level for a lightning bolt spell is 5, that's only a base DC 10 Spellcraft skill check, but this Spellcraft "DC to create a magic item increases by 5 for each prerequisite the caster does not meet."
So to create a javelin of lightning at caster level 5 without needing to use a charge from a wand of lightning bolt (or finding a dude to cast lightning bolt while you and he slave for a couple of days over this javelin of lightning or whatever) changes that Spellcraft skill check DC from 10 to only DC 15. Since a lot of folks who make magic items—wisely!—also ramp up their Spellcraft skills, not being able to meet directly a magic item's prerequisite or two is often considered a trivial impediment.
Note: The item creation feat prerequisite can't be bypassed by increasing the Spellcraft skill check DC. Further, spell prerequisites can't typically be bypassed when creating potions, spell completion magic items like scrolls, or spell trigger magic items like wands. For instance, a druid couldn't increase the Spellcraft DC to bypass the lightning bolt prerequisite of a wand of lightning bolt to create that item!
- You can create a Javelin of Lightning without knowing Lightning Bolt but increases the DC by 5.
- Having a Wand of Lightning Bolt won't help you because, although you can use an item to give you access to a spell you don't know, Lighting Bolt is not a Druid spell so a Druid can't use a Wand of Lightning Bolt.
- If you know someone who can use a Wand of Lightning Bolt like a wizard or sorcerer then you can cooperatively make the Javelin of Lighting.