In California, a law-abiding citizen can’t just buy a CS Military Tear Gas canister for self-protection; so start a tear gas training workshop.
They are required by law to take a special course to qualify to defend themselves.
Of course, criminals don’t need special courses to get lethal weapons.
Your state may not have such a law but, a good way to sell self-defense equipment is to hold workshops.
Here everyone can learn to use tear gas and other self-defense items.
Since crime in the streets is a serious concern, many elderly city residents seek out a training session with the hope of being able to defend themselves rather than becoming a victim.
Advertisement can be placed on Facebook.
Make the fee modest $10 to $15 and you can expect to sell tear gas to each person who attends.
Have some sessions in the evenings and others on Saturday.
Perhaps you can get your space free.
Schools, the American Legion, Elks Club, etc., often have halls where you could have a group workshop for no fee as a community service.
Use a Google search for current sources of tear gas canisters and other self-defense items.