At that price probably not a real 52/57. there are a couple of small differences. If it is a Vz52 with a chamber, don't buy it.
Make sure the rfle is marked Vz52/57, and that the reciever is notched for the barrel retaining pin. You can also do a search on this forum and the semi-auto military rifle forum for more information.
...iam pridem, ex quo suffragia nulli uendimus, effudit curas;
nam qui dabat olim imperium, fasces, legiones, omnia, nunc se
continet atque duas tantum res anxius optat, panem et circenses...