Even if the event is informal, it is important to capture in writing the details of any agreements that you make with vendors. These benefits may help to persuade you:
Roles and responsibilities are understood by all
There are no surprises about the terms of the agreement
Fee-related information is well-defined
In the end, if you opt not to make a Vendor Contract, you might not be able to experience any of the protections connected to having one in place.