Arrggh thats a sore subject. Plan for cash only, some may be set up for Cards and or Paypal, I dont get what the big problem is with cards, portable card machines have been around for a few years and since the advent of Smartphones and Mobile broadband It shouldn't be beyond the wit of man to setup to receive Paypal payments at an event like this, They tell you how much and what Paypal address, You whip out your phone go to Paypal and send them the money - and since it's Paypal you can set up to use a Credit card or Debit card...