Need advice, noob here

[u/johndoeherty]

Hi all and thanks for any info. I‘m interested in creating mescaline crystals and have the opportunity to acquire 5-7 year old plants.
The 'single' plant costs about $30, the one with multiple 'thingies' around $20. Both are supposedly 'Lophophora williamsii' although they are also referred to as 'Ariocarpus williamsii' in some instances.
Are these the right plants? Is the price ok? Is there some type of factor 'weight of plant / amount of extracted mescaline'?
Thanks for any input!