adding powers to an item

[Braininthejar]

The DM's Guide says that you can add new powers to an item only paying the difference in cost - what are the limits to this?

For example, I have found an elven cloak with magically deep pockets and I want to enchant it to act as a hat of disguise as well ( I figured a cloak is a legit body slot for a disguise item ) - so is it as easy as paying 1.5 of the cost of hat of disguise? (standard for new non-matching ability on a body slot item)

[kitep]

Yep.

Assuming the hat of disguise costs more than the magically deep pockets.

[Braininthejar]

I have no idea. What if it doesn't?

[ariasderros]

Because of a common house-rule.
If you have the cloak, have your DM approve the re-slot from hat to cloak, and add in the enchantment, then the RAW says that you pay 50% extra for the new enchantment.
If you don't have the cloak, and you want to make one with all three powers, you pay regular cost for the most expensive, then an extra 50% for each of the cheaper abilities.

Most groups house-rule that it always works like you're buying it new as far as whether you pay extra or not.

[kitep]

I have no idea. What if it doesn't?

If you have no idea what the deep pockets costs, then 1.5 * hat of disguise is a good way to go.