Used to give this all the time as a respiratory treatment (smells like rotten eggs) and IV route for Tylenol overdoses. Also given as a prep for kidney protection for people who have chronic kidney disease and have to take a test requiring IV contrast dye which is hard on the kidneys.

Cost depends on generic or brand name, but a 30 ml vial for respiratory inhalation treatments can be obtained for under $10 and the IV form around $130 . Known as Mucomyst or Acetadote for IV use.

Another drug that is cheap to put in the arsenal against covid 19

"Acetylcysteine, also known as N-acetylcysteine (NAC), is a medication that is used to treat paracetamol (acetaminophen) overdose, and to loosen thick mucus in individuals with cystic fibrosis or chronic obstructive pulmonary disease. It can be taken intravenously, by mouth, or inhaled as a mist."