I've looked online and there are a few options for buying a plastic cover for the 87 300D.

Anyone have any recommendations for where to look for a replacement dash, or for a cover that could be purchased online?

Also, my 300D has the MBTex, dark blue, anyone know the specific name of this color?

 

If you're planning on buying a used one it would be better if you saw it personally. All used ones will eventually crack no matter how well you care for them, you just need to makes sure you're getting your money's worth and make sure they try not to sell you one thats crap. If you pick one up from a dealer then you probably won't have to worry about it for the rest of the car's life.