Um, that's sorta some elitist bullshit buddy, but I see nevertheless where you're coming from, it is a sacred thing. Personally, I'm not going rooting around in the mexican countryside for rare cacti, and getting zonked out of my mind, only to die of heatstroke and get picked over by buzzards. And good luck finding some wise old Huichol tribesman who will walk you to his little slice of heaven and let you indulge yourself!
I have however ordered a 15 year old, 16 head san pedro off of a british site a couple of years ago, it came well wrapped and as fresh as the photo. I didn't bother drying it, and just indulged in the fresh heads with some other fellas. Was HIGHLY effective, lemme tell ya. Like I said though, you can find those bigass san pedro cacti at your average, well stocked, nursery. They are just unsuspecting looking large cactus- and will probably say the name on the little tag. The following link is a step-by-step guide on extraction of alkaloids.
You need to get your asses to some festivals- reggae on the river or burning man, and there you can find dried buttons that will thoroughly squeegy your third eye.
Also, you really ought to avoid mescaline until you've had your fair share of doses, and have gotten comfy with your headspace, because it will reaaaaally take you on a ride.
totse.com | Extracting Alkaloids from Trichocereus Cacti