Your yield for cocaine freebase extraction from coca leaves or coca tea is approx 0.48%
That being said, you'd need truck loads of leaves just to make 1kg of cocaine ( +/- 210 kilo for 1 kg of coke).
That infrastructure needed is probably not worth it.
What people do that synthesize coke in europe is importing cocaine freebase laced products like cement, textiles or others to then extract the freebase from the laced products with a chemical procedure.
Your best bet will probably be to find a cheap source for quality cocaine.