Wasp and hornet spray. It’s about $4 at the grocery store.
It’s also completely illegal and will get you thrown in jail. Read the label and take heed at the very first sentence on the can. Pepper spray is extremely effective and perfectly legal.
I’ll save you the time. The following has gotten people arrested and prosecuted for using WASP Spray even in cases of self defense. Then you get sued for the physical damages caused in civil court.
“It is a violation of federal law to use this product in a manner inconsistent with its labeling.”
Pepper spray is good enough for all LEO’s so it will obviously do for self defense.
Blinds them for about 15 minutes, exquisitely agonizing, and renders them so flailingly incoherent with pain that they can't even describe you to the police.
Have fun, kids! That's what demonstrators are for!