Enchanting Question: Always On

[fooflam]

I apologize in advance if this is posted somewhere, but I spent the last 1.5 hours searching for a reference to Always On for Enchanting items and was unable to find anything (even searched for "innate fatigue").

My question is this: When enchanting an item, is there an actual cost to include the "Always On" option? The Magic book didn't really say. I ask because my DM came up with a really cool, simple magical item that my character would like to recreate and sell, but I need to come up with a total point cost for casting (and then the materials cost after that, but that's the easy part).