Lynn Peavey
Gizmos and Gadgets
Armor Forensics
Sirchie
Ace
Evident
Police One
Spex Forensics
RC Forensic
Foster and Freeman
Oregon Rulers

If these companies don't have what you need, they can probably steer you to someone who does. Check out the Armor Forensic's Minutiea section for yet another set of useful essays and tutorials.

Oregon Rulers has a broad selection of police-specific scales and markers, some superior to anything available from other sources.