The real deal is $4,935. The knockoffs are less than $1,000. And honestly, I really can't tell much of a difference. The chair comes in over 15 leather colors with 4 different base wood. My favorite is the luggage leather with the oiled walnut veneer. I don't think the replicas have that many options to choose from but still a very good deal.
Real deal: Herman Miller
Replica sources: Modterior / LexMod / Manhattan Home Design / Poly + Bark / lazyBuddy