Consider offering sponsorship and promotional opportunities to non-exhibiting companies. For instance, credit card companies, financial services, hotel chains and car manufacturers may be eager to reach your attendees and exhibitor personnel. Indeed, if a show attracts a highly qualified audience, non-exhibitor opportunities can command premium prices.
What about a company that qualifies to be an exhibitor but only wants a sponsorship? Most shows will not allow this because they want everyone to have a presence on the floor. Others will take such a deal if that is the only way to get the company into the show. However, they require the sponsorship fee to be at least equal to the cost of a good size booth (such as a 20x30).