Ahh Treasure.....
Dude, there is a line in the DMG that goes something like.....
When facing NPC's thier equipment serves as thier "treasure"......that's why most PC's love encountering them over monsters.
Its at the begining of the "rewards" page.
Now there are several schools of thought here....
My old DM who thought that the "value of NPC equipment" was simply way too liberal and gave the 15th level frost giant fighter an enourmous masterwork axe a loin cloth and a few barrels of ale (most of which were used as missles against us)which was in his world plenty of treasure for a 6 man group of PC's at 10-12th level to share. He was easy to defeat....way too easy, if he'd have had +3 armor and a +3 weapon and a few wonderous itmes within the limits of the suggested tables he'd have been much harder to defeat, and IMHO much more of a challenge and therefore fun.....but hey, I've got my own game now.
I stick to the suggested equipment value strictly since I think that the balance of the game includes the assumption that advesarial NPC's have equipment appropriate to teir level. Just remember though that they will use everything at thier disposal to protect thier skins. If you give them a wand of harm make em use it and that goes for anything else. Fight them like they want to live.....