I don't know where you live, but in USA, you can order Tagamet for $10 off Amazon. I'm a bit younger myself. Going to shoot for 25g or so.
To respond to a few inquiries/points raised on this thread recently:
You can also get Tagamet from the grocery store (health/pharmacy section) in the US. You can check the Tagamet website and it will tell you which stores close to you stock it. I will be surprised if it's more than $5. That's the only missing piece for me now, but I'll get some this week.
Someone posted a screenshot (on another thread I believe) of the page from the updated PPH where Nitschke recommends 800mg of Tagamet 30 minutes before taking the SN. Thanks!
I understand that, if medically treated for SN poisoning, people make a full recovery. I collect that a person either dies from the poisoning, or they are treated and return to normal - no turning into a vegetable. I haven't so far encountered any accounts of an SN attempt where the person survived, with damage.
The lethal dose of SN is supposed to be as little as 1-3g for an adult human, according to the PPH. Therefore 15g is already a generous amount. I think this amount would be sufficient even for a healthy, young adult (like myself), or a larger person. But to each their own.
In the May or June 2018 PPH update, Nitschke recommends 10g SN with 4x10g metoclopramide. If you take more SN, you may want to increase the amount of meto you take. He has 1 10mg tablet for every 2.5g of SN. So for each additional 2.5g you take, you may want to take 1 extra 10mg meto pill. On this logic, I will take 6 meto tablets, since I will use 15g of SN. (But maybe there is a point at which taking more meto doesn't make a difference, or it causes negative effects - I don't know.)