When you receive an computer board and it's not in a ESD bag. It's safe to assume the manufacturer has placed it in an ESD safe box or packaging of some type.
If it came in an ESD bag when you got it, then, yeah you should have/get one.
But there has been times where I've gotten video cards that seemed to be in a plastic shell. I assure you that no manufacturer would be willing to sacrifice multiple video cards to ESD damage just to save a few bucks.