Regarding injection sites, I've always been told that it doesn't really matter where you inject, unless you are doing it incorrectly. It needs to be subcutaneous.
i've gotten glutathione, antibiotics, lidocaine, iv vitamins — all legit sources and worked as expected. stick with 1-2 vendors, the spam gets out of hand quick
The syringe supply shortage cycle is a recurring issue that doesn't get enough attention - pharmacy stockouts drive people toward paying premium prices for commodity medical supplies. Keeping a small reserve ahead of need is the only practical buffer against scrambling when the shortage hits.