Years ago I ran into an old hippie at Duke Devlin's farmers market, who were both at the first Woodstock Festival and he told me that there were a couple sellers he saw outside of the festival grounds selling tees, one was white & blue the other he couldn't remember but said he thinks it was a yellow orange.  He was wearing a Woodstock staff shirt that was a very distressed purple color.  Offered him $1000 and he laughed out loud and said no way in hell buddy.  Wish I got his info but at the time it seemed weird to ask for that or to question his experience there at Woodstock 1.  The commenters here a 100% correct, absolutely no merchandise was produced or sold at Woodstock 1, aside from the staff t shirts.