If you're going to use any injectable gear, then of course you're going to need some "darts." You can pick up syringes at your local pharmacy unless your state has certain restrictions. Also, you can purchase needles online. Just do a little searching around and you'll find several places that'll hook you up. Syringes will run you around 50 cents apiece. Note that it'll be more difficult to obtain needles (at least from the larger, more "legit" companies) if you live in California and Illinois. You'll usually need a doctor's prescription in those states. Still, if you look around enough, you can get what you need.
Most humans are very hard on themselves and, as a result, tend to accept criticism a little too easily. A lot of my friends are writers, and when someone criticizes one of them online, my immediate reaction tends to be, “That person is just a troll loser with no life.” My critics however, are almost certainly nuclear physicist supermodels, and “have some valid points.” I also tend to cling to the negative. There could be 30 very happy comments on an article, and I will find and focus on the one telling me I’m going to die alone because I wear overalls or something. (Spoiler alert: We all die alone.) Don’t do this. Instead, believe it when people tell you that you are awesome, and go ahead and assume that your haters are just that: haters.