Some people are repeatedly mistaking the Korean models to be the same as Clones, Replicas or China Maal.
Koren models of these S3/S4 etc are the same thing as T-Mobile or AT&T variant models, with different model number than the original.
They go for almost the same price as Original, and in some cases roughly 2-3k cheaper ... or even expensive.
The cheaper variants are Clones & Replicas. They can be easily distinguished from their build, and mostly will have mediaTek processors.