In misreading Fering's question I thought he was asking if making his item slotless would increase the price. I thought that was worthy of its own question.
When crafting a magic item with the craft wondrous item rules a GM may allow alterations to be made. If that alteration were to remove the slot requirement from an item, how much would it increase the price by?
For instance: a druid with the Craft Wondrous Item feat wants to make a slotless item with the same benefits at the Druid's Vestment. This item is normally costs 1,375gp to craft. What is the new crafting cost for the slotless version?