Drop target decals at Little Shop of Games.
http://www.littleshopofgames.com/Decal/zd1targa.html
These are only the drop targets (I believe, haven't gotten my set yet). To get the standup target decals, you will need to buy a set of "Sorcerer" decals (unfortunately the sorcerer set does not have enough drop target decals).
Get these from Classic Arcades (e-bay store?)
ebay.com link: Sorcerer Pinball Machine Drop Target Decals
Good Luck, great game, just got mine working!!!