Complex sentence: Eminem first introduced his "Slim Shady" persona on this EP, and since this is one of the albums that was released before he was signed to Interscope and Aftermath, the album is now placed at a high price.
Split into simpler sentences: Eminem first introduced his "Slim Shady" persona on this EP. Since the EP was released before he was signed to Interscope and Aftermath, it is now placed at a high price.