It's safest to suspend any judgement and save oneself the hassle and worry of being scammed until a more reliable supplier of N appears. I'd encourage all to not trust the subjective opinions of others while existing reports of unreliability on the current supplier exist as well. Better safe than sorry.
Regarding in-person way of buying N legally, the mexican aurhorities are a lot more aware about the issue than they were in 2006 when the earliest reports on the internet came afloat. Peru is a more viable choice. Directions to drug stores in Lima and relevant info are disclosed in the PPeH.
Also. As per site rules, any kind of exchange or sale between members is forbidden. Stay safe