Li Shenron, I apologize. Normally when I read a post about altering the XP system for magic item creation, I give my standard response (as above). But, now that I've actually had a chance to read your thread, and since I *ahem* did write the book on magic item creation, I'll give some advice.
I am generally in favor of utilizing the concept of hard-to-find components. The Artificer's Handbook spends a good deal of time outlining why just exchaning large amounts of wealth and XP for a magic item is not only unrealistic, but also really stupid, and IMHO, really lazy on WoTC's part.
Utilizing rare components mean that adventurers have to keep adventuring to find components, or at the very least earning money to buy them from merchants who might have certain curiosities available for sale. This is a much more realistic approach, IMO, and adds a lot of flavor, and potential plotlines to your game.
There is also a concept of instability introduced, whereby if the creator cuts corners, or uses bad materials, or whatever, the item has some sort of quirk or drawback as a result. This can also increase the playability aspect of magic items, and ensures that they are all unique.
There is a distinction drawn between permanent (continuous) items and items that have charges. Wands, potions, and scrolls are all in this category. The concept of an "expiration date" is already implemented for some magic items like candles in the DMG. These have an explicit duration. Our rules cover such things by implementing drawbacks and limitations.
Anyway, those are some of my thoughts. Let me know if you want me to expand on these any further.