The web site for TUL pens in www.tul.com. Office Max sells them. I, too, cannot find if/where the green pen is sold separately (only in multi-color packs). You might want to contact Office Max headquarters at the following address:
OfficeMax Corporate Headquarters
263 Shuman Blvd.
Naperville, IL 60563
Phone: 630-438-7800
Their customer service number is: 800-661-5931.
I did not see any eBay offers of TUL green pens either.
