Check out e-Bay. I picked up an authentic Chris Chambers jersey from there last year for around $90, brand new. The only difference between my jersey and the ones that you'd buy in the store is that it's Nike as opposed to Reebok (The NFL used to use Nike now they use Reebok, the only difference is the logo) and the fact that the stitching on the letters/patches isn't the same as those that you'd purchase elsewhere.
Believe me, I'm a person who likes to have the best if I'm going to purchase something (i.e. I'll usually pick the name over the knock-off) and I am totally and completely satisfied with my purchase of this jersey and am planning on purchasing a #34 on e-Bay when I get a chance.
Good luck and let me know if if you wind up getting a jersey from someone on e-Bay. :up: