First off I bought a Thomas Jones Jets jersey (authentic) The jersey itself, it is the same ones the players wear on field and looks straight out of the NFL shop. I then bought a Vilma and a Pennington jersey WHICH SUCK! They are very wide, and letters for the name on the back are fatter, plus the numbers have a different color to them. Can anyone tell me how to know wether or not its the same exact one before I go waste money? Im guessing you blow the picture up and compare them to the NFL SHOP pictures right? Plus the cheap jerseys are more wide, as the good ones will be the same width on the sides all the way down. Help me! lol

There are subtle difference between authentic and game won jerseys. You will find differences in the same jersey if bought at different places. Say you buy direct from the Jets website, NFLshops, Reebok & Ebay. You will get four different jerseys.
Ebay is dangerous unless you know what you are looking for. Even then, you can not be totally sure.

You have to know yourself what they look like and then compare. You can't blame a jersey you don't like on a seller if they show a picture.

Never buy a jersey off of ebay that doesnt have a picture or the picture doesnt look like the one on the Jets website and never buy from a person that has bad feedback ratings

You can get authentic jerseys on the bay , but you have to know what to look for when you see the pictures. every team has something unique about their jersey once you figure out what that is you can tell what is fake and real.

here is a good site to find the best jerseys