You don't make cathinone from Cathulus edulis. The plant makes it. You just extract it. An A/B extraction is what you want, but I hear it's not very stable so you would want to either make methcathinone or make a salt of it ( HCl, acetate, tartate, ECT, a lewis addict). As I recall
I'll give you this, the footnotes describe the process, and I'll say to you this; the plant leaves are almost certainly far more valuable than the chemicals which are easily synthesized. At 5g per kg of dirty mixed alkaloids or 3g of actual cathinone, that's 
$150 maybe+-. They sell everclear, which is 95% ethyl alcohol, but a lot of people just want a few beers.
www.ncbi.nlm.nih.gov
$150 maybe+-. They sell everclear, which is 95% ethyl alcohol, but a lot of people just want a few beers.Preparative HPLC for large scale isolation, and salting-out assisted liquid–liquid extraction based method for HPLC–DAD determination of khat (Catha edulis Forsk) alkaloids - PMC
Khat (Catha edulis Forsk) is an evergreen shrub of the Celastraceae family. It is widely cultivated in Yemen and East Africa, where its fresh leaves are habitually chewed for their momentary pleasures and stimulation as amphetamine-like effects. The ...
www.ncbi.nlm.nih.gov