What INT gear could I upgrade for the next 10-20 extra INT?

Something you might be overlooking is the stat requirements for these. In order to use a wisdom crystal and a dark crystal, you need to do it on level 80 stuff that needs 80 dex.

Another trick to getting a little INT boost is to get someone to give you MW. That's 4 more INT that cost you nothing but the paitence of a friend.