You have a few OEM color options, dark blue, grey (loop carpet), dark grey (velour), and beige. I've never seen a factory black carpet unless it was diyed black. and id advise NOT to buy an aftermarket molded carpet, the quality of of carpet is usually very poor or it doesn't fit worth a damn because they are made for pre 89 E30's that have a seperate underpad.
I learned this the hard way so take it from me you don't want to wast your money. your best off finding a used one in good shape or just pulling yours out and giving it a good cleaning.