I hope you find this guide helpful, It is all my opinion but I have fully researched the information.
I have been a vinyl picture disc collector for some time and lately following the passing of the legend that was MJ it has come to my attention that numerous sellers are taking advantage. All over ebay there are copies of promo picture discs, please look very closely all MJ's discs were re-released and still had promo on them, only the catalogue numbers were different.
The worst one at the moment is the huge amount of Dangerous discs selling for anything upto £100 sometimes more, if you look this disc can be bought for £19.99. The actual promo disc was made in 1993 and only 26 copies were pressed, these were given to Sony exec's when it was decided not to proceed with the idea, these are very very rare and recently one was sold on ebay for around £500, the difference being the clear vinyl edge where the normal version is black, and also the rare version plays richard clayderman not MJ. There is however a clear edged double album which was released in Brazil so please be carefully.
If you are buying a black vinyl MJ playing disc these are not rare you will find 1000's of them, still worth collecting mind you as they can't be around forever but don't pay through the nose. Of course the earlier release of the black version are worth that little bit more but not alot, do your homework and check the cat no.s