Just my 2 cents,
I am an active duty Special Operations Independent Duty Corpsman; and I personally never carried the powder. If you have the gauze that is laced with it, no big deal because even if it is "old / expired" you still have good gauze you can use to pack a wound pocket or lay over a wound.
I would challenge you to instead of buying more, invest in an extra tourniquet or two. If properly applied you don't have that constant concern of "what if that powder didn't give me proper hemorrhage control". Especially if this happens at night, you are much better off checking to make sure you don't have a distal pulse from where the tourniquet was applied vs. trying to find enough white light to see if the sand you just threw in a wound is working.
With tourniquets you have 6-8 hours before you are looking at irreversible tissue damage, I would hope in that time period you could either drive to a hospital or call life flight. If the thought of tissue damage concerns you deeply private message me and I will write you up our standard operating procedures for reducing a tourniquet into a pressure dressing; thus allowing enough blood flow to save the tissue.
Arterial bleeds are not to be taken lightly, and I know personally I would rather deal with tissue damage and be alive vs. bleed out in 90 seconds from an arterial bleed.