Okay, let me put together everything I can for the SN method. You'll need the following:
SN: The main thing for this method, Sodium Nitrite is easy enough to find. You're looking for >98% purity Nitrite. This chemical is sold without regulation and can be bought off Amazon, Ebay or any lab supplier in your area. 100g cost between 8 and 10€. This chemical is completely legal to own and is used during curation of meats to preserve their color. It's described as "White to yellowish powder/crystals" and it's said to have "slightly salty taste".
Very important: You're looking for Sodium Nitrite, not Sodium Nitrate; NaNO2, not NaNO3.
Should you not find it just by looking up Sodium Nitrite, look for: NaNO2, NNaO2 or Filmerine. Make sure you're buying what you want and that it's purity is high enough. For more information on it plus some industrial sellers, check Sodium Nitrite on Pubchem.
Antiemetics: Strong enough antiemetics for this method are not OTC, so you'll need to see your way around this. You're looking for Metoclopramide or any of it's commercial names, like Reglan/Primperam. This antiemetic needs to be a Dopamine blocker for it to work.
Antiemetics aren't 100% necessary for this method, however, just like with N, you wont accomplish anything if you end up puking it all out. This will also most likely be the bulk of the money you'll use during this method.
Acid Regulators: Another thing recommended in the PPH is raising your stomach's pH to make the SN more effective. This can be accomplished with drugs like Tagamet (The one recommended on the PPH, 800mg, which is to my knowledge OTC) or even bicarbonate, though not as useful.
Should anybody have more info on these topics, please tell me. I'm personally going to take Benzos before the SN as to diminish the supposed headaches it produces.