Sharp Shooter

Following along on caygad's math you can do the same thing or near the same thing buy going to your local pharmacy and purchasing several smal pill bottles with srew caps. The brown pill contained and the water proof lid would be very inexspensive + the color of the container protects the powder from degrading light rays including ultra-violet. The screw on caps provides a water tight container.

You can either pre-measure your charges or weigh if you choose to and then drop them into the pill bottles...