This one's really surprising. Eminem was Dr. Dre's pet project, and was a huge deal from almost the very first second he emerged in Detroit. Millions of people bought his debut single, and even more bought he debut album. So how is it that there's a whole 'Slim Shady' EP that hardly anybody owns, and many people are willing to pay thousands of dollars for?
The answer lies in the fact that it came before the single, and was mostly intended to be a promotional tool more than it was a commercial release. It was available to order if you knew where to look for it, and many rap fans who bought anything Dre told them to buy will have picked it up. If you were one of them, we hope you've kept it - the Slim Shady EP is now worth $15,000 or more on the open market.