I believe that loosing XP for making magical items is poor way of doing things. This is because u would not loose the ability to make a chair if u had made a table. If i asked you to make me a table. You would not turn around and say to me. wait a couple of days i need to go and kill 50 chickens to get enough xp to make your item. So i suggest that all magical items are given a skill rating. All creating magical items becomes a skill. this way you will have to forfeit other skills whilst yuou are learning to make better items. So say a bag of holding bag 1 is a skill of say 8 where as a Vorpal sword is most probably aaround 40 or so. You would need this skill to be able to make itl, Its easy and its for more logical. BAt the end of the day you need to be skilled to make things. still keep the ruling that you have to the spell in your spell list to be able to do it.