Say I had a bag of holding filled to the brim with (for whatever reason) clubs. And for whatever reason, I needed to reach into the bag and look not for a specific club, but just grab the first club that I could find with my reaching hand and pull it out.
What would the action cost of that be?
Retrieving a specific item from a bag of holding is a move action, unless the bag contains more than an ordinary backpack would hold, in which case retrieving a specific item is a full-round action. Magic items placed inside the bag do not offer any benefit to the character carrying the bag.
It would be a move action, even if the bag of holding contains more than an ordinary backpack (because you're removed the "specific" modifier), unless there's some other effect at work. You're still using the "Manipulate an Object" move action.
Manipulate an Item
Moving or manipulating an item is usually a move action.
This includes retrieving or putting away a stored item, picking up an item, moving a heavy object, and opening a door. Examples of this kind of action, along with whether they incur an attack of opportunity, are given in Table: Actions in Combat.
