For the life of me, I can't remember where I found this "formula". It's not mine, but I hope it helps. Straight fee - the promoter charges a booth fee, ranging from $10 to $1,500. This method is okay as long as your fee doesn't go over about $250. There are only so many bars of soap you can sell in two or three days, and there is a limit to how much inventory you can afford to make prior to the show. In my opinion, anything above $250 is pretty risky. In general, 1 to 3% of the total attending population will buy something at your booth. (A show of 3,000 people) Estimate 30 people- $510(low end) to 90 people- $1530 (high end) purchasing. In all probability, only 1/3 to 1/2 of the total in attendance will even venture by or into your booth. Expect to make: The “7x” rule: you can expect to make 7 to 10 times your entry fee. ($225) Multiply the entry fee times 7 for the low amount, and times 10 for the high number. ($1575 to $2250).