where to get warranty/VOID stickers?

[Purple Penguin]

I work on peoples systems in my town and we guarenteethe work. once in a while we get an idiot that comes back in saying we screwed up thier system and demands we buy them a new one.

when we re-open these systems it obvious they have opened them themselves and have no idea what the hell they're doing with the insides of thier systems (pieces pryed out with screwdrivers, wires pluged into the wrong spots, etc...)

so I'd like to get my own warranty sticker to put on the cases, the kind that leave a nice little "VOID" behind when removed.

does anyone know where I can get some of these that have a custom logo on them?

EDIT: I think I found a good EBAY AUCTION source. and they're customizable.