If you invest money in Engineering, you would expect new or improved products as a result. If you invest in sales & Marketing, it's not unreasonable to expect increased sales as a result. In either case if the results aren't commensurate with the investment, you find a different way to get a better result, that's just good business.
My experience in our booth (multiple companies) and visiting others is that no one is selling hard, they're there to expose you to their products and communicate the value. As a manufacturer we integrate with many others on the floor, so I spend my time talking to other manufacturers at the show to learn what they have and discuss how we might work together, and my experience is almost universally positive, people will take the time to talk to you, explain their products and answer any questions I might have, even if they know I'm not a potential sale.
My point was simply can something better be done with the investment? At that level of investment you have the base salary for another RSM, would adding another salesperson increase sales more than the long term benefit of exhibiting at ASIS? Could I do oneline or print advertising (70K = 2 almost full page adds a month)
Nevertheless, I agree with the comments that this industry only really needs one big show a year. ISC West has always been a more expensive show to do, but absolutely worthwhile in all respects, and to the comments on the lack of new product, we target our development efforts to having new product for ISC West, it's very difficult to have a major new release more than once a year.