You can favor either the convention or the artists and buyers on this one, or split the difference.  Does your art show need to attract more buyers and artists? If so, extra services are problably worthwhile.  If not, you may not want to expend the effort.
 
You can favor either the convention or the artists and buyers on this one, or split the difference.  Does your art show need to attract more buyers and artists? If so, extra services are problably worthwhile.  If not, you may not want to expend the effort.