For now, crafting / commissioning these items is disallowed, due to game-breaking rules mechanics. I am currently considering a revised way to implement these, if at all.
Under consideration are: a bigger cost multiplier, excluding Continuous versions of spell-effect items, or both, or something else entirely. I will post an update to this FAQ entry once I've come to a decision, and, am open to further suggestions until that time.
In the meantime, all the SRD pre-published items are allowed in play, as are custom crafted items that follow the SRD rules, besides the spell-effect types mentioned above.