Also remember transport costs. Warco and Chester bot run 44 tonne artics, believe me when I say these don't come cheap.
The bit a lot of people miss is say you do Alley Pally you have a catchment area of London and the South East because peole always make the excuse it's too far to travel.
So whilst you are at a show you are selling to your captive audience but the rest of the country is on hold.
And no matter how many shows you do at various venues you will always loose overseas orders. None of the traders are big enough to handle a show and keep the depot open as well. This also doesn't take into account just what you take as well so you will always get people wanting something you left behind as it didn't sell on previous shows.
And we won't mention the tyre kickers who just want to spend hours over a 10p order when you could be serving someone who is far more serious.
Another take on this probably no one else has though of and this from a time when I was just a member of Joe Public. I don't do shows for models, models don't interest me. I used to do shows to buy parts and materials and tools.
Now said tool man has paid very, very serious coin to stand this show and I roll up and some Herbert on the door wants to take £8 off me to enter.
WTF ?? I don't have to pay £8 to enter Warco's place, or Chester, or Chronos to spend my money why should I have to do it at a show especially when some of these traders are paying well into 5 figures [ no not a typo ]