It was dirt cheap back in the day and that's why it's not around now I would think. there's not much profit margin on a drug that will give you 9 hours of fun with no side effects. I'm not sure why it is expensive now, it's an easy google to make and any indian can have up to (16 oz.? in raw form) on them for religious purposes at any time IIRC.
https://en.wikipedia.org/wiki/MescalineI believe from experience that LSD builds in the system and does not leave so in effect whenever you do it again you are adding to the total. AFA leading to death it is by your actions while you are on the drug not by the drug itself. I had someone intentionally OD me on it and then try to punk me off which left him in intensive care and he almost died and me in a cell in segregation being told that I had killed him. that was the scariest week of my life, thinking you murdered someone is not somewhere you want to be. He attacked me and I instantly saw red until a crowd of people were yelling at me to stop and then my eyes focused and all I could see was a pool of blood I was standing in and the heel of my boot in his head. The next and last time I did LSD was about 7 years after that and I ended up walking down a 4 lane highway towards the cars calling them on and they were all swerving around me. After a few I realized what I was doing and left the highway. So in essence I CANNOT do LSD ever again. I could write a book (Ive done things people just don't believe) but am just a lazy fuk.

You can get Cacti all around, they're easy to find, legal, and fairly cheap. Pure Mescaline HCl however is a different story. It takes quite some effort to extract it out of cacti, and I'm not sure that part would even be legal and hence drive up the cost due to effort and well, legality. It's still dirt cheap if you compare it to any other form of entertainment, but it's quite expensive compared to LSD or mushrooms. Roughly ten times more expensive. Which is still nothing if you consider the fact that LSD costs less than a movie ticket (while providing more value).
As far as LSD "building in the system" is concerned. It's definitely excreted by the body, so if we're talking about long-term accumulation of residue that's not going to happen. It's true that any death surrounding LSD would be due to the actions during the trip or other external factors though. You would have to try really hard to ingest a lethal dose of it and would probably experience a loss of self before you could even ingest that much.
And damn, I've known a guy who just randomly stripped naked in the middle of the street whilst on MDMA (and lots of weed). Never seen anybody start yelling at cars on a highway though. Whatever happened to dosing at home or in a forest though?
