Just a quick one - can we confirm you put cash in - hit accept as fast as you can after they put in the item - then baCKSPCE - THEN ACCEPT AGAIN.
Also i am guessing you may be able to scam more people wit hitems of lower worth - arounfd the 20g mark etc and do more of them - rather than aiming for the 500g item for 50g - mainly becasue people are less cautious with smaller amounts - as a rule.