We are having a casual wedding party at a brewery. We are only renting the upstairs loft and the rest of the brewery will be open to the public. There was a band we really wanted so we were able to put them in touch with our venue - what they worked out was that they will charge at the door, but my guests will be on the guest list. I am essentially paying the per-head price for all of my guests and the band is making up the difference by having their fans pay at the door. How should I tip the band in this situation? Or do I? I imagine I do, but trying to decide how much. It's a unique situation so I'm not sure what the etiquette is for this. Thank you!