Hit or miss on getting a new Band 1 as it does miss features and Band 2 keeps going down in price. Also the build quality is a little low (make sure to get protectors for over the battery covers at the least)
Now a used Band 1, or any skin contact fitness device for that matter, I would never get. It's pressed up against the person for 20+ hours a day, 7 days a week, whether they're doing daily tasks or sweating up a storm. I know my Band rubber seems to absorb the sweat and sweat smell and even with an alcohol cleaning it can still be there... from a hygienic point I would not get a used one.