When you talk about the paint job, are you implying that it's the only thing that can verify it's authenticity? I do not have paperwork, but I think anyone familiar with NAS's work can immediately recognize it. Sid did good work...
But I agree, anyone interested in cosplay can get a cheaper...
I have a shiny green suit of Spartan armor, created by Nightmare Studios. It fits a 6'2" man and is in pristine condition. It comes from the personal collection of Sid Garrand (hence the size), and was used at SDCC to promote JoyRide Studios. It was also used in the pitch for master toy...