I don't believe so. I can almost guarantee those stickers aren't still being manufactured, especially considering that the Firefox branding has changed significantly since that campaign ran. You might be able to get one online, but it wouldn't be from an official Mozilla source. You can still find [https://github.com/mozilla/all-aboard/blob/1.0.0/data/media/headers/reward.png the image that was used on the sidebar] if you wanted to get one printed yourself, but the image included in the sidebar was far from a high-resolution image.