Scamming the Scammer

I was contacted by email by a prospective client who wanted to buy some mulch.  This happens all the time but this one was different.  What tipped me off was the request to ship mulch to Haiti!  I followed this one down the rabbit hole and couldn't shake the scammers.  Turns out that scammers themselves are far more gullible than they people they scam.  The exchanges below are hilarious.  In case you don't know much about mulch, we never irradiate it and there's no such thing as high tech foil wrap.  

They finally gave up when I raised their invoice to $400k.  

I'm unsure at exactly how they would get money out of me.  I have some guesses but I din't follow it through enough to find out.