As everybody has already said, using 3x cost is a tried and true formula for your initial pricing. Clearly, adjustments will need to be made given your specific situation, the event, the travel, the number of people, etc. so there's no calculator out there that will ever give you the right answer for your event/situation.
Bottom line is, if you take your total costs for the event and multiply it by three, at the very least you're giving yourself enough margin to cover your direct costs, most of your indirect costs, and probably put a little money into your pocket at the end of the day. At the same time, every event is different, and if you have to drive 200 miles round trip with your truck and trailer, that's a lot of added cost compared to hosting something in your own neighborhood. So, you need to adjust your prices accordingly to account for event specific requirements.
So, add up your costs and then start at 3x. Factor in any unique requirements that might make that number go up or down. Then look at what is leftover and see if it's enough money to make it worth your time doing the event. I don't know about you, but I don't want to bust my ass for 12+ hours all said and done just to come home with 100 bucks in my pocket, so in my book that would be a net loss. Your mileage may vary.