Making your own injectable Hyaluronic Acid Filler?

With the ability to purchase injectable grade cross- linked, deep and low molecular Hyaluronic Acid Powder, why don’t doctors consider purchasing at a fraction of the cost to make their own injectable syringes? Steril syringes, Proper HA molecular density depending on the area to be injected, and distilled water alone or Bacteriostatic water. I see company’s and manufacturers of fillers are beginning to sell Injectable grade HA powders for use as a filler or use in conjunction with derma rollers.