I'm guessing that the items created by enchant item can be as powerful or as trivial as the GM desires. Because each version of the spell would be found separately, a separate ritual would exist for creating each item, and it's totally up to the GM as to what rituals are discovered. But, as a general rule of thumb, the more powerful the item is, the greater the cost to create it. A ritual to create, say, an enchanted necklace that gives you a +2 bonus to perform checks would be pretty easy, but the tarot cards you mentioned would require at a minimum a sacrifice of permanent con points, possibly the bound soul of each creature to be summoned, maybe a human sacrifice or two, and years to complete. And lots of sanity.
On a not-quite related note, how does permanent ability drain work with spells like 'body warping' and 'mind transfer'? Could you take another body, burn its stat points, then switch back to your normal body? Also, does the str cost of mind transfer apply before or after the bodies are switched?