One definition of budget is the amount of money that is available for, required for, or assigned to a particular purpose.
In the world of operations a budget is not a suggestion. Depending upon the size of the event meeting the budget number is the difference in making money or losing it.
I’ve found the best way to achieve an accurate budget number which works is to first define the scope for the area whether it is temporary restrooms or fencing etc.
Once you have the scope then you can get at least one price based upon this scope. Once that price is achieved you have an accurate budget number and it takes the pressure off. At this point you can go back and work on ways to reduce that cost continuing the bid process.
There are others ways to hone in on a budget. If you have other years to draw from and the event is in the same place, budgets are a lot easier to start as you have a basis or control point.
This is all dependent upon where the event is located. If the event moves around it may be more difficult to use a previous year’s budget as costs will vary widely from California to New York.
If this is the case then I would go back to getting at least one price per area to start. The scope of work per area is unlikely to change that much year to year.
The budget is like every other plan you need to have. Spend some time on it and you will get it right.