It's forbidden to sell SN and a lot of other lab grade chemicals to "privatpersoner" in Sweden, not forbidden to buy or own but in order to get it from a retailer you need to be a company, a school or - I suppose - a scientist of some kind. You have to find a private seller if you want it.
N is practically impossible since it doesn't exist anymore. Pentobarbital is likely to be extremely hard to get, unless you know a sinister veterinarian, or go to South America.