For me it would have to be a commitmnent and not a one time thing b
The upfront cost to banners, blown up photos, hand outs etc would be too high for a "test" show. If you we're going to do multiple a year or the same local one over the next few years it would work.
This is a simple form of branding even if you don't see a money return.
One thing I would ask is the attendance over the last few years.