Looks like the antidote for Sarin is atropine:
http://www.meridianmeds.com/products-overview-antidote.aspx
And it requirers a prescription.
Here is some information on Sarin from the CDC:
http://www.bt.cdc.gov/agent/sarin/basics/facts.asp
“And it requirers a prescription.”
ha ha ha I look forward to the look on my MD’s face when I ask for a scrip for the kit!