You can't lower the caster level below what would be required to actually cast the spell, though; an item of Flight is going to likely require Caster Level 5, because that's needed to cast Fly (which is a 3rd level spell).
I don't have Eberron, so I have no idea how an artificer functions, but there you go.
ANY caster can, when creating an item, lower the caster level or raise it with more conventional items, like a wand or scroll; the minimum is still 'whatever you need to cast the spell,' and I'm not aware of any maximum -- I think you could have a CL 20 wand, if for some reason you thought that was a good idea.