I think the rules on using wish to improve existing items was already detailed either in one of the Tomes or my house rules. In any case, you know my interpretation now. The 15k is a hard cap on total item value, not a limit on the "upgrade" cost. We can drop the cost of adding the +1 starting enhancement bonus on armor and weapons though, since all magic armor and weapons have a scaling enhancement bonus with our rules. So you'd be able to add +3 total additional enhancements to armor, and +2 to weapons. I don't think I'll regret that...
So since the listed +3 armor in the MiC is about 9,000 gp (more if you include the masterwork costs, but I don't even know what the masterwork costs are for the Tome armor, if they exist), we could theoretically slap on some of the flat cost enhancements to boost that up to a full 15k?
Yes. And we're ignoring all non-magical costs entirely. So it can be adamantine or whatever "for free".
You could also add abilities from things not normally part of armor, like adding the power of a Lesser Metamagic Rod to your armor, if you want. (Raoul's sword is an example.) I don't really care, as long as you only have 8 items attuned, and those items are worth 15k or less in total. There is no extra cost for adding the properties of items together, either. So a set of armor with +3 worth of abilities and the power of a Lesser Metamagic Rod of Extend would be worth 12k (9k+3k).
Also, what costs do Tome magic item qualities like Dispelling in... wherever they put their magic item rules count as? I'm seeing basically a better version of the Dispelling enchantment listed there as a Lesser property and wondering what that means.
We've been ignoring their "Lesser, Medium, and Major" item classification system. They've basically done away with pricing things in terms of gold pieces entirely. A lesser property would probably be worth about a +1 or +2 enhancement equivalent, depending on what it does. So it would be available via Wish. Medium and Major items wouldn't.
Also, How angry would you get at me if I asked to upgrade my Darkstalker item with a Lightning Reflexes item for Evasion on top of it? Amusingly, that's actually about the only ability I can use from it for now aside from the basic +3 Reflex (since that would put my Ref save above my Balance mod). I figure Raoul might like it if he could fire off his AoEs without having to worry about hitting the one chick in the party with them.
Hmm... I think the Ring of Evasion is actually slightly overpriced, but probably not so much that you could combine it with your Darkstalker item. I'd let you have a Ring of Evasion with a Wish, but you wouldn't be able to upgrade it or add it to another item with a Wish.
And I'd
really prefer not to make up custom prices for magic items that grant Tome feats. If you get a bonus feat from a class feature, like your domains from Cloistered Cleric, we can "upgrade" that to the Tome version if it exists. For magic items, I don't think they should be able to provide Tome feats, at least not "lesser" items that you can get from Wish. They're just too damned good.
Later on, once you get to the point where items worth more than 15k are level appropriate (per the chart I posted in the House Rules thread), you can do a ritual (or however you want to describe/RP it) to add the properties of a Ring of Evasion to your Darkstalker item, if you want. We might also let Moderate magic items grant Tome feats, but I don't think they should be available via Wishing.