Try the Spell Slot Item Creation System. It's an updated version of the system presented originally in the Artificer's Handbook and can be downloaded for free from post #3 here:
http://www.enworld.org/forum/general-rpg-rules-discussion/240200-artificer-handbook-update.html
If you want the actual Artificer's Handbook, you can still buy the pdf here:
MEG: Artificer's Handbook [PJR291] - $9.95 : Your Games Now, Publisher Co-Op
Getting hold of a print copy of the book is probably going to be more difficult.
I read that link, and remember that post! Wow, that was out of left field.
It amazes me that this topic continues to come up all the time. I'm glad to know that I have a few followers that can spread the word for me since I don't spend very much time here anymore.
I've probably spent more time thinking about magic item creation than a rational person should. I really like the Artificer's Handbook method, but embarking down that path, one should understand that it really does muck around with the core economics QUITE a bit. GMs utilizing it, really probably do need to be prepared for how much cheaper some things are going to be. Optionally, they can modify the formula's GP constant from 10 to something like 15 or 20 if they feel like it's too low. But that's kind of self-defeating, since one of the side goals of the system is to tone down the economics. It always bothered me that high level characters were expected to carry around a bank's vault worth of coins. It's kind of ridiculous if you really stop and think about it.
Also, the system really tends to lend itself extremely well to a more grim/low magic game. Since a big focus of a lot of the chapters from the complete book were devoted to components. Idea being that one of the easiest and most logical ways to eliminate the artificial XP burden on item creation was to just require "tongue of newt" and "eye of frog". Of course, GM's can easily handwave that for "mundane" magic items by just saying "Ok, you spend 1,000gp on all the crap you need at the market square for you item." It gets difficult to come up with fancy, expensive ingredients for a magic item, especially if the thing is a damned stick - like a staff of the woodlands, for example. Good luck with that one.
To this end, I started working on an E6/E8 specific adaptation to those rules last year. Here is that document. It has a few new things in it, like alchemical variations for potions, and some wand charts near the back.
Lastly, and more on-topic, I've NEVER used XP in any game I've ever ran. Even in 2nd edition. Admittedly, it's harder in 3rd. This isn't because I'm some avante garde rebel, it's simply because I'm lazy. I always handwave it "Congratulations! You're now 4th level". Easy. Plus, I tend to be kind of cavalier with treasure nowadays - I actually award things like ability score increases, skill points, and action points nowadays.
For magic items, the documents linked and attached should suffice.
For spells, it's a little harder, but fortunately, there aren't that many spells that require XP. At one time, I had a list of them, and I'd gone through each of them and decided how to replace XP in them. I can't find it to save my life, though.
But basically, I removed permanency - I found it too unworkable. For any spell that summons a creature, I require a favor. Something like Planar Ally, et al. When summoned, the creature demands a magic item, cash, or a favor (GM's discretion). For things like wish/limited wish, I'd actually worked them in a similar way as Planar Ally - if you use wish/lw to just replicate a lower level spell, it doesn't require anything (which if you think about it, is not all that unlike just leaving a spell slot blank). But if you use it to actually "wish" for something, then it actually summons an Efreeti or Noble Djinni who then "grants" the wish for you on your behalf. So, get the wording right!! And then, of course, they're going to want something in return...
