Due to budgetary constraints, most of my gear is now brewed by yours truly. Simple as pie. Find a reputable powder source. Dissolve the powder in appropriate amount of benzyl alcohol and benzyl benzoate (solvents), add your sterile carrier (oil, ethyl oleate), sterilize if you want(30min at 200deg in the oven, 30min in freezer repeat 3x), use a sterile syringe filter and filter into sterile vial. Voila.
I consider sterilizing the mixture as optional because the benzyl alcohol will do that for you if you give it some time (i.e., don't make it and shoot, let it sit for a week).