There are many, many scams going around about special event tickets being sold online such as for the Super Bowl, concerts or other sporting events. You need to be very careful whenever purchasing something from someone you don't know.
Purchase from Reputable Companies
Keep the saying in mind "if it sounds too good to be true, it's probably not true." It's much safer to purchase tickets from a reputable company or the venue itself. You may not get the "great deal" but at least you'll know what you've purchased is legitimate.