Cocaine is one of the most difficult syntheses to accomplish and the
DEA has only busted a single lab where they were attempting this. The
problem is chirality. The molecules made by the synthesis are not all
active and must be separated by using optically active tartrate
crystals. It is not easy.
You can make cocaine analogues much more potent, much easier. Look up
WIN 36,065-2 or some of the arecoline derivatives which have much less
of a stimulant effect and more euphoria.