Never thought about mixing with saline to cut the sting, that's smart actually. There's a shop selling vials for $9 but I've got like 29 left so I'll be using them forever. Will it break down faster if I do that though?
needles are cheap. use a fresh one for every step—one to draw, a new one to inject. sterile water is already sterile lol, no need to dunk in alcohol. keep it simple with the mixture, don't overthink it.