u/TemporaryBad1108

I am a new colector and I would like to buy some older batman sets like jokerland or arkham asylum breakout but i see that a lot of sets have 30-40% below the market value new sealed sets from Singapore or Malaysia with thousand of positive reviews. My question is that is there any type of black market replicating 1 on 1 sets like for clothes and if yes how could i verify that is not?