Not to burst anyones bubble here, but just because the number and letters are sewn on doesn't make it authentic. If you paid $48 for an "authentic" jersey, it isn't authentic. Here is the breakdown.
The cheap jerseys with the screen print name and number. Sells for $40-$50 in the stores (Champs, JC Penny, etc.).
The next step up is the authenreplica jersey. This sells for about $100-$125. It has the number and letters sewn on. It could pass for an authentic jersey. I thought they were authentic at first.
The authentic jerseys sell for nothing less than $190ish to $325ish depending on the team. It has the number and letters sewn on and is pretty heavy compared to the authenreplica jersey. Also some stretchy material in the shoulder area.
There are some cases were you could get authentic jerseys discounted especially when a player leaves that team and goes to another.
Those who bought their jersey on E-bay for $50 most likely don't have an authentic jersey. I'd say 90% of the jerseys sold on E-Bay aren't authentic. As you could see by the replies above the majority of people can't tell the difference between an authenreplica and authentic jersey. If you don't want to plunk down the extra money an authenreplica is the way to go. If i was walking by you from 15 feet away I most likely wouldn't know the difference. If you were 2 feet in front of me, I could tell. Hope this helps.